11 Marmy, P., Kruml, T., Low cycle fatigue of Eurofer 97, Journal of
Nuclear Materials, 377 (2008) 1, 52–58, doi:10.1016/j.jnucmat.
2008.02.054
12 M. Mi{ovi}, N. Tadi}, M. Ja}imovi}, M. Janji}, Deformations and
Velocities during the Cold Rolling of Aluminium Alloys, Mater.
Tehnol., 50 (2016) 1, 59-67, doi:10.17222/mit.2014.250
13 A. Grajcar, Microstructure Evolution of Advanced High-Strength
Trip-Aided Bainitic Steel, Mater. Tehnol., 49 (2015) 5, 715–720,
doi:10.17222/mit.2014.154
14 B. [u{tar{i~, I. Paulin, M. Godec, S. Glode`, M. [ori, J. Flasker, A.
Koro{ec, S. Kores, G. Abramovi~, DSC/TG of Al-based Alloyed
Powders for P/M Applications, Mater. Tehnol., 48 (2014) 4, 439–450
15 F. Tehovnik, J. Burja, B. Podgornik, M. Godec, F. Vode, Micro-
structural evolution of Inconel 625 during hot rolling, Mater. Tehnol.,
49 (2015) 5, 899–904, doi:10.17222/mit.2015.274
B. MA[EK et al.: INFLUENCE OF THERMOMECHANICAL TREATMENT ON THE GRAIN-GROWTH BEHAVIOUR ...
768 Materiali in tehnologije / Materials and technology 51 (2017) 5, 759–768
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
769–773
ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH
THE USE OF HIGH-RESOLUTION ELECTRON MICROSCOPY
AND COMPUTER SIMULATION
RAZISKAVE OBORIN V ALUMINIJEVIH ZLITINAH Z
VISOKORESOLUCIJSKO ELEKTRONSKO MIKROSKOPIJO IN
RA^UNALNI[KO SIMULACIJO
Krzysztof Matus, Anna Tomiczek, Klaudiusz Go³ombek, Miros³awa Pawlyta
Silesian University of Technology, Institute of Engineering Materials and Biomaterials, 18A Konarskiego Str.,
44100 Gliwice, Poland
krzysztof.matus@polsl.pl
Prejem rokopisa – received: 2016-07-27; sprejem za objavo – accepted for publication: 2017-01-27
doi:10.17222/mit.2016.226
This paper presents the results of the tests using high-resolution transmission electron microscopy (HRTEM) with both
transmission and scanning modes, as well as energy-dispersive-spectroscopy (EDS) investigation of the AlSi9Cu alloy after
laser surface remelting. The possibility of using a computer simulation to identify precipitates in the analysed alloy was also
explored. The obtained results and computer simulations were compared. Moreover, this article presents the advantages of the
computer aid in solving the diffraction patterns and precipitates in supercell simulations.
Keywords: precipitation, crystallography, TEM, computer simulations
V prispevku so predstavljeni rezultati preiskave AlSi9Cu zlitine z laserskim pretaljevanjem povr{in z uporabo transmisijske
elektronske mikroskopije z visoko lo~ljivostjo (angl. HRTEM) na dva na~ina: s transmisijskim skeniranjem, kot tudi z
energijsko disperzijsko spektroskopijo (angl. EDS). Z uporabo ra~unalni{ke simulacije je bila preiskana mo`nost identifikacije
delcev v analizirani zlitini. Dobljeni rezultati in ra~unalni{ke simulacije so bili primerjani. Poleg tega ~lanek predstavlja
prednosti ra~unalni{ke simulacije pri {tudiji vzorcev difrakcije in oborin v posameznih stanjih celic.
Klju~ne besede: oborine, kristalografija, TEM, ra~unalni{ke simulacije
1 INTRODUCTION
Aluminium alloys are the most widely used alloys in
modern technology, mainly due to high specific strength
and low density. Other factors behind the widespread
distribution of aluminium alloys are their excellent
electrical conductivity and high corrosion resistance.1,2
The use of laser surface treatment to improve the utility
properties of aluminium alloys allows the remelting of
the surface layer of the material or its enrichment with
alloy elements. The remelting of the material surface and
rapid crystallisation allow an improvement of the mecha-
nical properties of alloys, mainly in the field of abrasion
resistance and tribological properties of the surface.
Through the generation of plenty of fine precipitates, the
strength is increased as well. The influence of alloying
element precipitates on aluminium alloys is a complex
issue and it is still one of the most promising topics in
materials science.3–7
Laser surface treatment ensures that the processed
material obtains new properties due to the rapid disper-
sion of the heat from the melted zone. This phenomenon
enables the crystallisation of very fine precipitates to
occur. Laser remelting can be used for small and large
elements. The most common alloyed layers have a thick-
ness from 0.3 3 mm to about 3 mm. A layer formed by
remelting usually has a high homogeneity as well as a
fine crystalline structure. The use of the laser technology
makes it possible to obtain surface layers with high con-
tents of alloying elements and a unique combination of
elements that conventional alloys rarely contain.8–11
Generally, the laser surface treatment is accom-
plished with two methods, which differ from one another
based on how the alloying addition is introduced to the
surface layer (which is schematically presented in
Figure 1). When the surface of a material is subjected to
a laser beam and then melted, the process is called
remelting (Figure 1a). When an alloying material is
applied to a surface and then melted with a laser beam
(most of the materials are added in the forms of tapes,
pastes or powders), the process is called alloying (Figure
1b).12,13
This article aims to identify the precipitates in an alu-
minium alloy after the laser treatment using transmission
electron microscopy and computer simulations.
2 EXPERIMENTAL PART
For the experimental procedure, cast AlSi9Cu alumi-
nium alloy was used. Its average chemical composition
is shown in Table 1. This alloy was subjected to
Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773 769
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
UDK 620.1:669.715:621.385.833:004.942 ISSN 1580-2949
Original scientific article/Izvirni znanstveni ~lanek MTAEC9, 51(5)769(2017)
remelting using high-power diode laser (HPDL) ROFIN
SINAR DL 020 with a radiation wavelength of 940±5
nm and a laser power of 2 kW with a spot size of
1.8 mm × 6.8 mm and argon as the shielding gas.
Table 1: Chemical composition of AlSi9Cu alloy, in mass fractions
(w/%)
Si Cu Fe Mn Mg Ti Al
9.0 1.0 0.7 0.4 0.3 0.3 balance
Samples for transmission-electron-microscopy
(TEM) observations were prepared as thin foils, where
the Gatan PIPS 691 precision ion polishing system was
used to prepare them. Studies were carried out using a
scanning transmission electron microscope S/TEM Titan
80-300 type (FEI, USA), operated at 300 kV and
equipped with a EDAX Li-drifted Si EDS detector
(Philips Electronic Instruments Corp. PV97-61850 ME).
Electron-microscopy observations were performed with
a probe Cs-corrected S/TEM Titan 80-300 FEI micro-
scope, equipped with an EDAX EDS detector (energy
resolution of 132 eV). HRTEM images (300 kV, Cs = 1.2
mm, 0.2 nm point resolution) were recorded using only a
condenser lens aperture, and thus without an objective
lens aperture. HAADF-STEM images were obtained
with a HAADF STEM detector (Model Fischione 3000).
A convergence angle of 0.974° was used with the
HAADF detector’s inner collection angle of 5.443°. The
probe size used was about 0.1 nm. The diffraction
patterns were collected by exploiting both the selected
area electron diffraction (SAED) and Fourier trans-
formations from HRTEM and HAADF images.
Chemical-composition examinations were carried out
using energy-dispersive spectroscopy (EDS) for the
identification of the precipitates which occurred in the
samples. To perform a simulation of unit cells, the
CrystalMaker software was used.14 The simulation of
supercells and the results of electron diffraction were
realised with the software "Química de Solidos y
Catalisis, Estructura y Química de Nanomateriales"
developed at the University of Cadiz.15,16
3 RESULTS AND DISCUSSION
Despite a low content of titanium in the analysed
material (0.3 %, Table 1), microscopic observations
revealed the presence and dense occurrence of titanium
nanoprecipitates in the shape of sticks, sized approxi-
mately 250 nm × 50 nm (Figures 2 and 3). The reason
for this is the fact that it is a high-melting-point element.
At the time of the laser alloying, the volume of the
material was treated with a laser beam and then rapidly
melted and cooled down. When lowering the
temperature, the precipitates of titanium were the first to
crystallize. After melting all the elements, including
titanium, there was an even distribution. The amount of
titanium is limited, so the size of the crystallites formed
did not exceed 250 nm. The boundary between the
matrix and the titanium precipitates is a favorable
nucleation area for the other precipitates to grow on
titanium rods. The EDS map presents the titanium
distribution and determines the localization of titanium
precipitates in the aluminium matrix (Figure 3).
Figure 4 shows an enlarged view of one of the pre-
cipitates containing Ti. The size of the precipitate is
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
770 Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 1: Diagram of laser treatment: a) remelting, b) alloying12,13
Figure 3: STEM-HAADF/EDS map which presents a magnification
of the area from Figure 2 and shows the distribution of titanium in the
aluminium matrix
Figure 2: STEM-HAADF image of titanium precipitates in an alumi-
nium-alloy matrix
approximately 150 nm × 30 nm. The contrast in the
STEM-HAADF image indicates a difference in the
chemical composition between the precipitate and the
matrix. The matrix area and three areas characterised by
differing contrasts (different chemical compositions) and
structures (different phases) are marked by A and B–D,
respectively. The results of the chemical analysis of the
selected areas are presented in Figure 5, in graphs A-D,
and Table 2.
Table 2: Chemical compositions of the areas marked with letters A–D
in Figure 5 (in amount fractions, a/%)
Al (K) Cu (K) Mg (K) Si (K) Ti (K)
point A 93.95 6.04 – – –
point B 18.92 15.04 39.83 26.19 –
point C 67.65 5.03 3.70 23.60 –
point D 75.64 6.35 – 5.75 12.24
In the centre of Figure 4, the precipitate marked with
symbol D, which contains mainly Ti, Al and Si, is
shown. The observed precipitate had an irregular, elon-
gated shape and a size of approximately 100 nm × 20 nm.
The grain boundary between the precipitate with
titanium and the matrix served as the nucleation point for
the other precipitates. Copper results were affected by a
holder and by the pole pieces, which were made of
copper. There were at least two other types of precipi-
tates, which were marked with symbols B and C. The
phase marked as B consisted of Al, Mg, Si and Cu
(Figure 5b). The intensities of the Mg, Si and Cu peaks
(K lines) were higher than that of the matrix. At the
phase boundary between the aluminium matrix and the
precipitate marked as B, two smaller precipitates,
marked as C, can be noticed. The chemical composition
of precipitate C was similar to that of precipitate B (Al,
Si, Mg and Cu), as shown in Figure 5c, but the relative
intensities of the peaks were different. Detected Mg
content in precipitate C was practically at the back-
ground level. A fast Fourier transform (FFT) of the
precipitate marked with the letter B is presented in
Figure 6a. Compared to the EDS spectrum, the
measurement of the spacings and angles in the FFT, with
its high-resolution image, and a computer simulation of
the diffraction pattern allow the identification of the
precipitate marked with letter B as the Q phase (with a
chemical composition close to Al3Cu2Mg9Si7). A
comparison of the simulated electron diffraction and the
experimental one allows determining the orientation of
the Q-phase precipitate as [001] (Figure 6b).
The unit cell of the Q phase was simulated along the
[001] direction (Figure 7). This data was necessary to
create a supercell in the Q phase (Figure 8a) with its
characteristic arrangement of atoms and marked regular
shape between the copper atoms. This was then adapted
to an enlarged HAADF image of the investigated preci-
pitate (Figure 8b). The HAADF detector enabled the
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773 771
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 5: Results of the chemical analysis of the areas marked with letters A–D in Figure 5
Figure 4: STEM-HAADF image of a complex precipitate in the
aluminium matrix
remelting using high-power diode laser (HPDL) ROFIN
SINAR DL 020 with a radiation wavelength of 940±5
nm and a laser power of 2 kW with a spot size of
1.8 mm × 6.8 mm and argon as the shielding gas.
Table 1: Chemical composition of AlSi9Cu alloy, in mass fractions
(w/%)
Si Cu Fe Mn Mg Ti Al
9.0 1.0 0.7 0.4 0.3 0.3 balance
Samples for transmission-electron-microscopy
(TEM) observations were prepared as thin foils, where
the Gatan PIPS 691 precision ion polishing system was
used to prepare them. Studies were carried out using a
scanning transmission electron microscope S/TEM Titan
80-300 type (FEI, USA), operated at 300 kV and
equipped with a EDAX Li-drifted Si EDS detector
(Philips Electronic Instruments Corp. PV97-61850 ME).
Electron-microscopy observations were performed with
a probe Cs-corrected S/TEM Titan 80-300 FEI micro-
scope, equipped with an EDAX EDS detector (energy
resolution of 132 eV). HRTEM images (300 kV, Cs = 1.2
mm, 0.2 nm point resolution) were recorded using only a
condenser lens aperture, and thus without an objective
lens aperture. HAADF-STEM images were obtained
with a HAADF STEM detector (Model Fischione 3000).
A convergence angle of 0.974° was used with the
HAADF detector’s inner collection angle of 5.443°. The
probe size used was about 0.1 nm. The diffraction
patterns were collected by exploiting both the selected
area electron diffraction (SAED) and Fourier trans-
formations from HRTEM and HAADF images.
Chemical-composition examinations were carried out
using energy-dispersive spectroscopy (EDS) for the
identification of the precipitates which occurred in the
samples. To perform a simulation of unit cells, the
CrystalMaker software was used.14 The simulation of
supercells and the results of electron diffraction were
realised with the software "Química de Solidos y
Catalisis, Estructura y Química de Nanomateriales"
developed at the University of Cadiz.15,16
3 RESULTS AND DISCUSSION
Despite a low content of titanium in the analysed
material (0.3 %, Table 1), microscopic observations
revealed the presence and dense occurrence of titanium
nanoprecipitates in the shape of sticks, sized approxi-
mately 250 nm × 50 nm (Figures 2 and 3). The reason
for this is the fact that it is a high-melting-point element.
At the time of the laser alloying, the volume of the
material was treated with a laser beam and then rapidly
melted and cooled down. When lowering the
temperature, the precipitates of titanium were the first to
crystallize. After melting all the elements, including
titanium, there was an even distribution. The amount of
titanium is limited, so the size of the crystallites formed
did not exceed 250 nm. The boundary between the
matrix and the titanium precipitates is a favorable
nucleation area for the other precipitates to grow on
titanium rods. The EDS map presents the titanium
distribution and determines the localization of titanium
precipitates in the aluminium matrix (Figure 3).
Figure 4 shows an enlarged view of one of the pre-
cipitates containing Ti. The size of the precipitate is
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
770 Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 1: Diagram of laser treatment: a) remelting, b) alloying12,13
Figure 3: STEM-HAADF/EDS map which presents a magnification
of the area from Figure 2 and shows the distribution of titanium in the
aluminium matrix
Figure 2: STEM-HAADF image of titanium precipitates in an alumi-
nium-alloy matrix
approximately 150 nm × 30 nm. The contrast in the
STEM-HAADF image indicates a difference in the
chemical composition between the precipitate and the
matrix. The matrix area and three areas characterised by
differing contrasts (different chemical compositions) and
structures (different phases) are marked by A and B–D,
respectively. The results of the chemical analysis of the
selected areas are presented in Figure 5, in graphs A-D,
and Table 2.
Table 2: Chemical compositions of the areas marked with letters A–D
in Figure 5 (in amount fractions, a/%)
Al (K) Cu (K) Mg (K) Si (K) Ti (K)
point A 93.95 6.04 – – –
point B 18.92 15.04 39.83 26.19 –
point C 67.65 5.03 3.70 23.60 –
point D 75.64 6.35 – 5.75 12.24
In the centre of Figure 4, the precipitate marked with
symbol D, which contains mainly Ti, Al and Si, is
shown. The observed precipitate had an irregular, elon-
gated shape and a size of approximately 100 nm × 20 nm.
The grain boundary between the precipitate with
titanium and the matrix served as the nucleation point for
the other precipitates. Copper results were affected by a
holder and by the pole pieces, which were made of
copper. There were at least two other types of precipi-
tates, which were marked with symbols B and C. The
phase marked as B consisted of Al, Mg, Si and Cu
(Figure 5b). The intensities of the Mg, Si and Cu peaks
(K lines) were higher than that of the matrix. At the
phase boundary between the aluminium matrix and the
precipitate marked as B, two smaller precipitates,
marked as C, can be noticed. The chemical composition
of precipitate C was similar to that of precipitate B (Al,
Si, Mg and Cu), as shown in Figure 5c, but the relative
intensities of the peaks were different. Detected Mg
content in precipitate C was practically at the back-
ground level. A fast Fourier transform (FFT) of the
precipitate marked with the letter B is presented in
Figure 6a. Compared to the EDS spectrum, the
measurement of the spacings and angles in the FFT, with
its high-resolution image, and a computer simulation of
the diffraction pattern allow the identification of the
precipitate marked with letter B as the Q phase (with a
chemical composition close to Al3Cu2Mg9Si7). A
comparison of the simulated electron diffraction and the
experimental one allows determining the orientation of
the Q-phase precipitate as [001] (Figure 6b).
The unit cell of the Q phase was simulated along the
[001] direction (Figure 7). This data was necessary to
create a supercell in the Q phase (Figure 8a) with its
characteristic arrangement of atoms and marked regular
shape between the copper atoms. This was then adapted
to an enlarged HAADF image of the investigated preci-
pitate (Figure 8b). The HAADF detector enabled the
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773 771
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 5: Results of the chemical analysis of the areas marked with letters A–D in Figure 5
Figure 4: STEM-HAADF image of a complex precipitate in the
aluminium matrix
distinction and contrast between the columns of atoms
containing elements of differentiated value Z. Images
were obtained by recording the intensity of the scattered
electrons as a function of the incident beam position on
the sample surface. Cu has the highest value of Z,
therefore the copper atoms were characterized as having
the best contrast, or the brightest points.
Using the same method, the area marked as C in
Figure 4 was identified as the U1 phase (MgAl2Si2), and
area D was determined as the TiAl3 phase.17,18
The precipitates created during the laser remelting of
aluminium alloys have very complex chemical compo-
sitions and crystallographic structures (Figures 5 and 7
and Table 2). The interface between the matrix and the
large amount of precipitation is a unique place to
increase further the creation of the precipitates, which
are successfully identified as the participations of the
complex U1 and Q phases. Particularly the precipitates
of the Q phase, which is a major equilibrium phase of the
Al-Mg-Si-Cu system, are noteworthy. The Q phase
belongs to the P-6 space group with lattice parameters:
a = b = 0.1039 nm, c = 0.409 nm, and  =  = 90°,  =
120°.17
4 CONCLUSIONS
Laser surface treatment, due to its requirement for a
large amount of energy, leads to a dissolution of the
surface layers of alloys due to a rapid dissipation of heat
into the interior of the material. This causes the remelted
material to solidify very quickly, resulting in the
formation of fine precipitates of high-melting elements,
which are unique places for the nucleation of other
precipitates. This type of treatment can increase the
hardness due to the refinement of the microstructure. The
completed research determined that the phase that forms
first during the cooling was TiAl3, on which other
precipitates with complex chemical compositions such as
the precipitates of the Q and U1 phases grew. With the
help of the computer simulations allowing the identifi-
cation of the phases of the process, the process was
shortened in comparison to the research using the data-
bases on a computer. Moreover, the use of simulation
software to obtain diffraction patterns simplified the
processes of identifying the phases and their orientations.
The simulation of unit cells and supercells allowed the
matching of the simulated phases with their high-reso-
lution images.
Acknowledgment
This publication was financed by the Ministry of
Science and Higher Education of Poland as the statutory
financial grant of the Faculty of Mechanical Engineer-
ing, SUT.
5 REFERENCES
1 C. Cayron, P. A. Buffat, Transmission electron microscopy study of
the ’ phase (Al–Mg–Si alloys) and QC phase (Al–Cu–Mg–Si
alloys): ordering mechanism and crystallographic structure, Acta
Mater., 48 (2000), 2639–2653, doi:10.1016/S1359-6454(00)00057-4
2 D. J. Chakrabarti, D. E. Laughlin, Phase relations and precipitation
in Al–Mg–Si alloys with Cu additions, Prog. Mater. Sci., 49 (2004),
389–410, doi:10.1016/S0079-6425(03)00031-8
3 A. L. Garcia-Garcia, I. Dominguez-Lopez, L. Lopez-Jimenez, J. D.
O. Barceinas-Sanchez, Comparative quantification and statistical
analysis of ’ and  precipitates in aluminum alloy AA7075-T651 by
TEM and AFM, Mater. Charact., 87 (2014), 116–124, doi:10.1016/
j.matchar.2013.11.007
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
772 Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 8: a) Q-phase supercell with the selected pattern of copper
atoms and b) this pattern registered on the HAADF image
Figure 7: Unit cell of precipitate Q in the [001] direction
Figure 6: a) Fast Fourier transform (FFT) of a high-resolution image
and b) simulation of the diffraction pattern of the Q-phase precipitate
in the [001] direction
4 N. K. Mukhopadhyay, H. J. Chang, J. Y. Lee, D. H. Kim, Electron
microscopy of an icosahedral phase in a rapidly solidified
Al18Mg3Mn2 complex metallic alloy, Scr. Mater., 59 (2008),
1119–1122, doi:10.1016/j.scriptamat.2008.07.024
5 A. Biswas, D. J. Siegel, D. N. Seidman, Compositional evolution of
Q-phase precipitates in an aluminum alloy, Acta Mater., 75 (2014),
322–336, doi:10.1016/j.actamat.2014.05.001
6 F. Delmas, M. J. Casanove, P. Lours, A. Couret, A. Coujou, Quan-
titative TEM study of the precipitation microstructure in aluminium
alloy Al(MgSiCu) 6056 T6, Mater. Sci. Eng. A, 373 (2004),
doi:10.1016/j.msea.2003.12.068
7 W. Yang, S. Ji, M. Wang, Z. Li, Precipitation behaviour of Al–Zn–
Mg–Cu alloy and diffraction analysis from ’ precipitates in four
variants, J. Alloys Compounds, 610 (2014), 623–629, doi:10.1016/
j.jallcom.2014.05.061
8 Z. Hu, L. Wan, S. Wu, H. Wu, X. Liu, Microstructure and mecha-
nical properties of high strength die-casting Al–Mg–Si–Mn alloy,
Mater. Des., 46 (2013), 451–456, doi:10.1016/j.matdes.2012.10.020
9 J. Aguilar, M. Fehlbier, A. Ludwig, A. Bührig-Polaczek, P. R. Sahm,
Non-equilibrium globular microstructure suitable for semisolid
casting of light metal alloys by rapid slug cooling technology
(RSCT), Mater. Sci. Eng. A, 375–377 (2004), 651–655, doi:10.1016/
j.msea.2003.10.091
10 W. M. Lee, M. A. Zikry, High strain-rate modeling of the interfacial
effects of dispersed particles in high strength aluminum alloys, Int. J.
Solids Struct., 49 (2012), 3291–3300, doi:10.1016/j.ijsolstr.2012.
07.003
11 J. F. Nie, B. C. Muddle, On the form of the age-hardening response
in high strength aluminium alloys, Mater. Sci. Eng. A, 319–321
(2001), 448–451, doi:10.1016/S0921-5093(01)01054-1
12 J. C. Betts, Laser surface modification of aluminium and magnesium
alloys, Surf. Eng. Light Alloys, Woodhead Publishing, 2010,
444–474, doi:10.1533/9781845699451.2.444
13 H. C. Man, C. T. Kwok, T. M. Yue, Cavitation erosion and corrosion
behaviour of laser surface alloyed MMC of SiC and Si3N4 on Al
alloy AA6061, Surf. Coat. Technol., 132 (2000), 11–20,
doi:10.1016/S0257-8972(00)00729-5
14 http://www.crystalmaker.com
15 C. López-Cartes, J. A. Pérez-Omil, J. M. Pintado, J. J. Calvino,
Z. C. Kang, L. Eyring, Rare-earth oxides with fluorite-related struc-
tures: Their systematic investigation using HREM images, image
simulations and electron diffraction pattern simulations, Ultramicro-
scopy 80 (1999), 19–39, doi:10.1016/S0304-3991(99)00067-4
16 S. Bernal, F. J. Botana, J. J. Calvino, C. Lopez-Cartes, J. A. Perez-
Omil, J. M. Rodriguez-Izquierdo, The interpretation of HREM
images of supported metal catalysts using image simulation: profile
view images, Ultramicroscopy, 72 (1998), 135–164, doi:10.1016/
S0304-3991(98)00009-6
17 R.-K. Pan, L. Ma, First-principles study on the elastic properties of
B’ and Q phase in Al–Mg–Si (–Cu) alloys, Phys. Scr., 87 (2013),
doi:10.1088/0031-8949/87/01/015601
18 S. J. Andersen, C. D. Marioara, R. Vissers, A. Frøseth, H. W. Zand-
bergen, The structural relation between precipitates in Al–Mg–Si
alloys, the Al-matrix and diamond silicon, with emphasis on the
trigonal phase U1-MgAl2Si2, Mat. Sci. Eng. A – Struct., 444,
(2007), 157–169, doi:10.1016/j.msea.2006.08.084
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
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MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
distinction and contrast between the columns of atoms
containing elements of differentiated value Z. Images
were obtained by recording the intensity of the scattered
electrons as a function of the incident beam position on
the sample surface. Cu has the highest value of Z,
therefore the copper atoms were characterized as having
the best contrast, or the brightest points.
Using the same method, the area marked as C in
Figure 4 was identified as the U1 phase (MgAl2Si2), and
area D was determined as the TiAl3 phase.17,18
The precipitates created during the laser remelting of
aluminium alloys have very complex chemical compo-
sitions and crystallographic structures (Figures 5 and 7
and Table 2). The interface between the matrix and the
large amount of precipitation is a unique place to
increase further the creation of the precipitates, which
are successfully identified as the participations of the
complex U1 and Q phases. Particularly the precipitates
of the Q phase, which is a major equilibrium phase of the
Al-Mg-Si-Cu system, are noteworthy. The Q phase
belongs to the P-6 space group with lattice parameters:
a = b = 0.1039 nm, c = 0.409 nm, and  =  = 90°,  =
120°.17
4 CONCLUSIONS
Laser surface treatment, due to its requirement for a
large amount of energy, leads to a dissolution of the
surface layers of alloys due to a rapid dissipation of heat
into the interior of the material. This causes the remelted
material to solidify very quickly, resulting in the
formation of fine precipitates of high-melting elements,
which are unique places for the nucleation of other
precipitates. This type of treatment can increase the
hardness due to the refinement of the microstructure. The
completed research determined that the phase that forms
first during the cooling was TiAl3, on which other
precipitates with complex chemical compositions such as
the precipitates of the Q and U1 phases grew. With the
help of the computer simulations allowing the identifi-
cation of the phases of the process, the process was
shortened in comparison to the research using the data-
bases on a computer. Moreover, the use of simulation
software to obtain diffraction patterns simplified the
processes of identifying the phases and their orientations.
The simulation of unit cells and supercells allowed the
matching of the simulated phases with their high-reso-
lution images.
Acknowledgment
This publication was financed by the Ministry of
Science and Higher Education of Poland as the statutory
financial grant of the Faculty of Mechanical Engineer-
ing, SUT.
5 REFERENCES
1 C. Cayron, P. A. Buffat, Transmission electron microscopy study of
the ’ phase (Al–Mg–Si alloys) and QC phase (Al–Cu–Mg–Si
alloys): ordering mechanism and crystallographic structure, Acta
Mater., 48 (2000), 2639–2653, doi:10.1016/S1359-6454(00)00057-4
2 D. J. Chakrabarti, D. E. Laughlin, Phase relations and precipitation
in Al–Mg–Si alloys with Cu additions, Prog. Mater. Sci., 49 (2004),
389–410, doi:10.1016/S0079-6425(03)00031-8
3 A. L. Garcia-Garcia, I. Dominguez-Lopez, L. Lopez-Jimenez, J. D.
O. Barceinas-Sanchez, Comparative quantification and statistical
analysis of ’ and  precipitates in aluminum alloy AA7075-T651 by
TEM and AFM, Mater. Charact., 87 (2014), 116–124, doi:10.1016/
j.matchar.2013.11.007
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
772 Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS
Figure 8: a) Q-phase supercell with the selected pattern of copper
atoms and b) this pattern registered on the HAADF image
Figure 7: Unit cell of precipitate Q in the [001] direction
Figure 6: a) Fast Fourier transform (FFT) of a high-resolution image
and b) simulation of the diffraction pattern of the Q-phase precipitate
in the [001] direction
4 N. K. Mukhopadhyay, H. J. Chang, J. Y. Lee, D. H. Kim, Electron
microscopy of an icosahedral phase in a rapidly solidified
Al18Mg3Mn2 complex metallic alloy, Scr. Mater., 59 (2008),
1119–1122, doi:10.1016/j.scriptamat.2008.07.024
5 A. Biswas, D. J. Siegel, D. N. Seidman, Compositional evolution of
Q-phase precipitates in an aluminum alloy, Acta Mater., 75 (2014),
322–336, doi:10.1016/j.actamat.2014.05.001
6 F. Delmas, M. J. Casanove, P. Lours, A. Couret, A. Coujou, Quan-
titative TEM study of the precipitation microstructure in aluminium
alloy Al(MgSiCu) 6056 T6, Mater. Sci. Eng. A, 373 (2004),
doi:10.1016/j.msea.2003.12.068
7 W. Yang, S. Ji, M. Wang, Z. Li, Precipitation behaviour of Al–Zn–
Mg–Cu alloy and diffraction analysis from ’ precipitates in four
variants, J. Alloys Compounds, 610 (2014), 623–629, doi:10.1016/
j.jallcom.2014.05.061
8 Z. Hu, L. Wan, S. Wu, H. Wu, X. Liu, Microstructure and mecha-
nical properties of high strength die-casting Al–Mg–Si–Mn alloy,
Mater. Des., 46 (2013), 451–456, doi:10.1016/j.matdes.2012.10.020
9 J. Aguilar, M. Fehlbier, A. Ludwig, A. Bührig-Polaczek, P. R. Sahm,
Non-equilibrium globular microstructure suitable for semisolid
casting of light metal alloys by rapid slug cooling technology
(RSCT), Mater. Sci. Eng. A, 375–377 (2004), 651–655, doi:10.1016/
j.msea.2003.10.091
10 W. M. Lee, M. A. Zikry, High strain-rate modeling of the interfacial
effects of dispersed particles in high strength aluminum alloys, Int. J.
Solids Struct., 49 (2012), 3291–3300, doi:10.1016/j.ijsolstr.2012.
07.003
11 J. F. Nie, B. C. Muddle, On the form of the age-hardening response
in high strength aluminium alloys, Mater. Sci. Eng. A, 319–321
(2001), 448–451, doi:10.1016/S0921-5093(01)01054-1
12 J. C. Betts, Laser surface modification of aluminium and magnesium
alloys, Surf. Eng. Light Alloys, Woodhead Publishing, 2010,
444–474, doi:10.1533/9781845699451.2.444
13 H. C. Man, C. T. Kwok, T. M. Yue, Cavitation erosion and corrosion
behaviour of laser surface alloyed MMC of SiC and Si3N4 on Al
alloy AA6061, Surf. Coat. Technol., 132 (2000), 11–20,
doi:10.1016/S0257-8972(00)00729-5
14 http://www.crystalmaker.com
15 C. López-Cartes, J. A. Pérez-Omil, J. M. Pintado, J. J. Calvino,
Z. C. Kang, L. Eyring, Rare-earth oxides with fluorite-related struc-
tures: Their systematic investigation using HREM images, image
simulations and electron diffraction pattern simulations, Ultramicro-
scopy 80 (1999), 19–39, doi:10.1016/S0304-3991(99)00067-4
16 S. Bernal, F. J. Botana, J. J. Calvino, C. Lopez-Cartes, J. A. Perez-
Omil, J. M. Rodriguez-Izquierdo, The interpretation of HREM
images of supported metal catalysts using image simulation: profile
view images, Ultramicroscopy, 72 (1998), 135–164, doi:10.1016/
S0304-3991(98)00009-6
17 R.-K. Pan, L. Ma, First-principles study on the elastic properties of
B’ and Q phase in Al–Mg–Si (–Cu) alloys, Phys. Scr., 87 (2013),
doi:10.1088/0031-8949/87/01/015601
18 S. J. Andersen, C. D. Marioara, R. Vissers, A. Frøseth, H. W. Zand-
bergen, The structural relation between precipitates in Al–Mg–Si
alloys, the Al-matrix and diamond silicon, with emphasis on the
trigonal phase U1-MgAl2Si2, Mat. Sci. Eng. A – Struct., 444,
(2007), 157–169, doi:10.1016/j.msea.2006.08.084
K. MATUS et al.: ANALYSIS OF PRECIPITATES IN ALUMINIUM ALLOYS WITH THE USE OF HIGH-RESOLUTION ...
Materiali in tehnologije / Materials and technology 51 (2017) 5, 769–773 773
MATERIALI IN TEHNOLOGIJE/MATERIALS AND TECHNOLOGY (1967–2017) – 50 LET/50 YEARS