Microstructure and mechanical properties of Al-Ti-Zr intermetallic compounds prepared by vacuum hot pressing

Al-Ti-Zr ternary system with different compositions (Al 40, 41, 43, 50 at.%) was synthesized by in-situ reaction of ZrH2, TiH2 and Al powders through vacuum hot pressing at 1400 degrees C for 0.5 h under 40.8 MPa. The microstructure, micro hardness, fracture toughness, and flexural strength of Al-Ti-Zr alloys were investigated. AlTi2 + TiAl and Zr(Ti)Al + Al-3(Ti, Zr)(5) new lamellar structures were found in the samples. Micro hardness increased while flexural strength and fracture toughness decreased with the increasing of the ratio of Al-Zr intermetallics. Flexural strength and fracture toughness of Al43 were the highest reaching up to 396.0 MPa and 6.0 MPa.m(1/2), respectively. The fracture modes of Ti3Al + TiAl, AlTi2 + TiAl and Zr(Ti)Al + Al-3(Ti, Zr)(5) lamellar structures were transgranular fractures, while fracture modes of Al-Zr intermetallics were intergranular fractures. The crack tip blunting and the effect of crack deflecting in Ti3Al + TiAl lamella led to increasing of flexural strength and fracture toughness. Besides, interlayer tearing of the three lamellar structures led to rising of flexural strength. (C) 2018 Elsevier Ltd. All rights reserved.