Preparation, microstructure and mechanical properties of multicomponent Ni3Al-bonded cermets

Abstract

Ni3Al intermetallic compound was synthesized by mechanical milling mixture of elemental Ni and Al powder after 20h milling; mechanical alloying (MA) first generated a Ni(Al) solid solution that transformed to Ni3Al intermetallic compound on further milling. Ti(C,N)–xNi3Al cermets were prepared through conventional powder metallurgy route at different sintering temperatures. The microstructure and mechanical properties of Ni3Al-bonded cermets sintered at different temperatures with different contents of Ni3Al were systemically studied. The dark core-gray rim carbide grains and/or dark core-white inner rim-gray outer rim carbide grains embedded in light-gray Ni3Al based binder phase were observed. Abnormal grains growth happened in all cermets and these grains tend to be lath like grains in this research. Moreover, with the rise of sintering temperature, the phenomenon of abnormal grains growth becomes more obvious, resulting in rapid growth of individual grains. Generally, transverse rupture strength (TRS) of cermets increased with the ascent of Ni3Al content and sintering temperature, however, it reached a peak value 1131±80.3MPa, when sintering temperature was 1450°C. HRA of cermets ascended firstly and then dropped down with the increase of binder content and sintering temperature. Fracture toughness (K1C) increased with Ni3Al content and got a peak value 16.1±0.55MPam1/2.