Refinement and characterisation of a thermodynamically stable #beta#-[Ni(Al,Ti)]-#beta#'-[Ni_2AlTi]- #gamma#'-[Ni_3(Al,Ti)] metal-metal composite

摘要

The Ni-Al-Ti system contains threeintermetallic phases, #gamma#', #beta#, and #beta#'which have complementary properties. The objective ofthe present investigation was to coextrude these threephases to form a metal-metal composite (MeMeC) andinvestigate the mechanical properties and failuremechanisms of such a material. High strengths,comparable with that of the strongest constituent phase,have been recorded for the MeMeC material. Strengthis maintained at a constant level up to 500beg C abovewhich it falls progressively. The compressive strain tofailure is considerably greater that that expected formonolithic #beta# or #beta#' phases. It has been shownthat the interfaces between nominally single phaseregions provide lines of weakness along which crackspropagate during compressive loading. Preliminaryattempts to strengthen the interfaces by a 24 h heattreatment at 900beg C have been carried out.