522 KB18 KB200020242014Cagala, MichalČegan, TomášJuřica, JanKawulok, PetrKursa, MiroslavRusz, StanislavVontorová, Jiřinaletnik:48številka:6str. 831-835COBISSID:1113258ISSN:1580-2949URN:URN:NBN:SI:doc-M681MWSRenInštitut za kovinske materiale in tehnologijeMateriali in tehnologijecarbidescarbonkarbidimechanical propertiesmehanske lastnostimicrostructuremikrostrukturaogljiktitanium aluminidestitanovi aluminidiEffect of Ti2AlC particles on the microstructure and elevated-temperature-deformation properties of gamma-TiAl alloys| Vpliv delcev Ti2AlC na mikrostrukturo in deformacijske lastnosti zlitin gama-TiAl pri povišani temperaturi|The g-TiAl intermetallics with and without amount fractions x = 0.3 % of yttrium and with different carbon amount fractions ranging from 0.9 % to 1.6 % were prepared by vacuum-induction melting in a graphite crucible. Different amounts of carbon were obtained by varying the time of melting. The resulting samples had large rod-like carbides with volume fractions 0.6 % to 3.7 % Ti2AlC in the lamellar matrix consisting of the alternating lamellas of g-TiAl and a2-Ti3Al phases. It was found that the grain size of the matrix decreases with the increasing volume fraction of Ti2AlC carbides from 430 %m to 35 %m. In addition, finer carbides with a similar composition were observed. Their size was below 1 %m and they appear mainly at the grain boundaries and also inside the lamellar grains. Compression testing revealed that all the samples had a relatively high yield strength at elevated temperature, from 917 MPa to 623 MPa at 600 °C and from 608 MPa to 547 MPa at 800 °C, but the best strength and the best yield strength were found for the sample with the lowest amount of the large rod-like Ti2AlC carbides. From these results it is concluded that the strengthening at an elevated temperature is a result of C in the solid solution and small carbide precipitates rather than of the rod-like Ti2AlC carbidesIntermetalne zlitine g-TiAl z množinskim deležem itrija x = 0,3 % in brez njega ter z različno vsebnostjo množinskega deleža ogljika od 0,9 % do 1,6 % so bile izdelane z vakuumskim indukcijskim pretaljevanjem v grafitnem lončku. Različne vsebnosti ogljika so bile dobljene pri različnih časih taljenja. Dobljeni vzorci so imeli volumenski delež Ti2AlC od 0,6 % do 3,7 % velikih paličastih karbidov v lamelarni osnovi iz lamel faz g-TiAl in a2-Ti3Al. Ugotovljeno je bilo, da se z večanjem volumenskega deleža Ti2AlC-karbidov velikost zrn osnove zmanjšuje od 430 %m do 35 %m. Opazilo se je tudi, da imajo drobnejši karbidi podobno sestavo. Njihova velikost je manjša od 1 %m, pojavljajo se večinoma po mejah zrn in tudi v lamelarnih zrnih. Tlačni preizkus je odkril, da imajo vsi vzorci relativno visoko mejo tečenja pri povišanih temperaturah: od 917 MPa do 623 MPa pri 600 °C in od 608 MPa do 547 MPa pri 800 °C. Najvišjo trdnost in najvišjo mejo tečenja je imel vzorec z najmanjšo vsebnostjo velikih, paličastih Ti2AlC-karbidov. Iz rezultatov je razvidno, da je utrjevanje pri povišanih temperaturah bolj posledica ogljika v trdni raztopini in drobnih karbidnih izločkov kot pa velikih paličastih Ti2AlC-karbidovTEXTznanstveno časopisjejournalsSlovenian National E-content AggregatorNational and University Library of SloveniaInštitut za kovinske materiale in tehnologije