Microstructure and phases constitution of Cr3C2/Ni3Al composites prepared by hot isostatic pressing (HIP)

Abstract

The Cr3Cj/Ni3Al composite materials were prepared by hot isostatic pressing (HIP) at 1160°C and 100MPa. Microstructure and phases constitution of the composite materials were investigated. The results indicate that the original Cr3C2 particle firstly dissolves into Cr and C atoms and then diffuses into the matrix. During the cooling process, the dissolved Cr and C atoms transformed into a stable Cr7C3 structure. Also, an uphill diffusion phenomenon is observed for Fe element from the matrix to the Cr7C3 carbide phase, which is attributed to the easy formation of stable carbides of Fe element in Ni3Al alloy with C element. And, the Fe atoms substitute a part of Cr atoms in Cr7C3 carbides and form a diffusion phase with M7 C3 (M for Cr, Fe) structure. When the original Cr3Q2 particles are large, it cannot be completely dissolved during the high temperature period. The undissolved core of Cr3C2 particles still remain the Cr3C2 structure after the cooling process. The Cr3C2/Ni3 Al composite materials are composed of Cr3C2 hard core phase, M7C3 diffusion phase and ?-Ni3Al matrix material phase. The Cr3C2 hard core phase and the ?'-Ni3Al matrix created a good diffusion bonding by the formed M7C3 diffusion phase. Therefore, the Cr3C2 particle on the worn surface does not peel off and the groove is interrupted around the chromium carbides during the wear test, resulting in significantly improved wear resistance of Cr3C2/Ni3Al composites.