Microstructure and mechanical properties of (Al,Cr)3Ti based alloy with different Al additions

Al67Ti25Cr8 powders with cubic L12 ordered structural characteristic are formed by mechanical alloying and annealing process. X% Al–Al67Ti25Cr8 composites (X = 5, 10, 15, 20 wt.%) were fabricated by hot isostatic pressing. Porosity of bulk specimen, first decreases, and then increases with increasing Al content at same test conditions. The 10 wt.% Al–Al67Ti25Cr8 composite exhibited good compactibility, whilst the 20 wt.% Al–Al67Ti25Cr8 composite exhibited honeycomb-shaped structures due to the expanding and shrinkage of Al. Owing to Al additions jamming the micro-pores and micro-cracks, Al–Al67Ti25Cr8 composites with suitable Al contents (10–15 wt.%) exhibit improved strength (0.2%YS as 420 MPa and UTS as 469 MPa) and fracture toughness (10.4 MPa m0.5). However, too high Al additions caused the deterioration of mechanical properties.