Phase Stability, Microstructure and Mechanical Properties in the Multi-Phse Alloys Based on the L12-Ni3(Al,Be)

Abstract

AbstractIntermetallic alloys based on the Ll2 Ni3(Al,Be) phase in the ternary Ni-Al-Bc system are prepared so that the alloys are multi-phase with the B2 intermetallic compound NiBe and a Ni primary solid solution denoted as (Ni). Such three-phase alloys, Ni-16 to 20 at%Al-10 at%Be, exhibit good room temperature ductility as measured by four-point bending. In order to examine the phase stabilities and relations among constituent phases, a vertical section of the ternary system is constructed at a constant 10 at%Bc mainly by differential thermal analysis. It is found that improvement in room temperature ductility can be achieved by the formation of a fine mixture of constituent phases during invariant reactions during solidification, which is further enhanced by the co-existence of the Ll2 phase formed as the primary solidification phase.