ISSN: 1003-6326
CN: 43-1239/TG
CODEN: TNMCEW

Vol. 27    No. 3    March 2017

Effect of synthesis parameters on structural and mechanical properties of Ti3Al-Nb-Mo intermetallic compound obtained by powder metallurgy techniques
Biljana DIM?I?, Jelena STA?I?, Jovana RU?I?, Du?an BO?I?
(Institute of Nuclear Sciences “Vin?a”, University of Belgrade, P. O. Box 522, Belgrade 11001, Serbia)
Abstract: The influence of microstructure, heat treatment and alloying addition on mechanical and fracture properties of Ti3Al-based intermetallic at room and elevated temperatures was studied. Ti3Al-11Nb-1Mo (mole fraction, %) alloy was consolidated via powder metallurgy processing by mechanical alloying (MA) and hot pressing (HP). MA powders were characterized using XRD and SEM-EDS. Optimum MA duration was 25 h and HP conditions of 1350 °C, 2 h, 35 MPa. After HP, solution treatment at 1050 °C for 1 h and water quenching α2+β Widmanst?tten microstructure is present, while subsequent aging at 800 °C during 24 h induces small content of O-phase. High fraction of β-phase is a direct consequence of Mo. Compression tests were performed from room temperature to 750 °C in vacuum. The yield strength of compacts increases with temperature up to 250 °C (pyramidal slip systems activation), after which it decreases. Ductility increases throughout the whole temperature range. The presence of O phase contributed to ductility increase in aged alloys, while negligibly lowering yield strength. Registered drop in the yield strength of aged alloys compared with non-aged ones was mostly influenced by precipitation of α″2 particles. Mixed fracture modes are operative at all temperatures.
Key words: titanium aluminide; mechanical alloying; hot pressing; thermal treating; compressive properties
Superintended by The China Association for Science and Technology (CAST)
Sponsored by The Nonferrous Metals Society of China (NFSOC)
Managed by Central South University (CSU)