Microstructure and properties of Ni3Si alloyed with Cr fabricated by self-propagating high-temperature synthesis casting route

Abstract

Ni3Si alloys with 20, 30, and 40 wt pct Cr were fabricated by self-propagating high-temperature synthesis casting at 543 K. Thermite reaction (Cr2O3+5CrO3+12Al=7Cr+6Al2O3) was used in Cr alloying. The method is simple and economical when used to prepare Ni3Si-based alloys. The process is described in detail. The alloys were analyzed with X-ray diffraction (XRD) and scanning electron microscopy (SEM) with X-ray energy dispersive spectroscopy (EDS). The results showed the alloys mainly consisted of Ni3Si and Ni5Si2 with dissolved Cr and Cr phases. Phases and microstructures of the alloys varied with Cr content. Microhardness, bending and compressive strength, and wear rate of the alloys were measured. Microhardness of the alloys was higher than that of Ni3Si without Cr and increased with Cr content. Bending and compressive strength of the alloys were better than those of the Ni3Si without Cr, and those of the alloy with 30 wt pct Cr were the highest. The wear rate of the alloys was lower than that of the Ni3Si without Cr and decreased with Cr content.