Study on the Precipitation Strengthening in Ni-Al-Cr Alloy System

Abstract

Transmission electron microscopic investigation has been performed concerning the effect of precipitation on the mechanical properties in Ni3Al- and NiAl-based intermetallics containing various types of fine precipitates. In an L12-ordered Ni3Al alloy with 4 mol. % of chromium and 0.2-3.0 mol % of carbon, fine octahedral precipitates of M23C6 type carbide, which has the cube-cube orientation relationship with the matrix, appear during aging. Typical Orowan loops are formed in Ni3Al containing fine dispersions of M23C6 particles. On the other hand, B2-ordered NiAl hardens appreciably by the precipitation of coherent a-Cr particles. By aging at temperatures around 973 K