Refinement and characterisation of a thermodynamically stable β-[Ni(Al,Ti)]-β′-[Ni{sub}2AlTi]-γ′-[Ni{sub}3(Al,Ti)] metal-metal composite

摘要

The Ni-Al-Ti system contains three intermetallic phases, γ', β, and β' which have complementary properties. The objective of the present investigation was to coextrude these three phases to form a metal-metal composite (MeMeC) and investigate the mechanical properties and failure mechanisms of such a material. High strengths, comparable with that of the strongest constituent phase, have been recorded for the MeMeC material. Strength is maintained at a constant level up to 500℃ above which it falls progressively. The compressive strain to failure is considerably greater that that expected for monolithic β or β' phases. It has been shown that the interfaces between nominally single phase regions provide lines of weakness along which cracks propagate during compressive loading. Preliminary attempts to strengthen the interfaces by a 24 h heat treatment at 900℃ have been carried out.