Effect of synthesis parameters on structural and mechanical properties of Ti3Al-Nb-Mo intermetallic compound obtained by powder metallurgy techniques
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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 degrees C, 2 h, 35 MPa. After HP, solution treatment at 1050 degrees C for 1 h and water quenching alpha(2)+beta WidmanstAtten microstructure is present, while subsequent aging at 800 degrees C during 24 h induces small content of O-phase. High fraction of beta-phase is a direct consequence of Mo. Compression tests were performed from room temperature to 750 degrees C in vacuum. The yield strength of compacts increases with temperature up to 250 degrees C (pyramidal slip systems activation), after which it decreases. Ductility increases throughout the whole tem...perature 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 a. 2 particles. Mixed fracture modes are operative at all temperatures.