The effect of Cr addition on mechanical and chemical properties of Ni 3Si alloys

Abstract

The alloying behavior and microstructure of the Ni–Si–Cr ternary alloys were firstly characterized by optical microscopy, X-ray diffraction (XRD) and scanning electron microscopy (SEM) with electron probe analysis. The microstructures of the Ni–Si–Cr ternary alloys consisted of largely dispersed Ni 5Si 2 phase and finely precipitated Ni 3Si phase in Ni solid solution. Then, the high-temperature mechanical properties, three-point bend test, oxidation and corrosion properties were investigated. The Ni–Si–Cr ternary alloys showed significant strengthening over a wide range of temperatures, and also large compressive plastic deformation at high temperatures. The strength and fracture toughness at ambient temperatures were correlated with the volume fraction of the Ni 5Si 2 phase. The Ni–Si–Cr ternary alloys showed substantially improved oxidation resistance in air at 1173 K, comparing with the Ni 3Si and Ni 3(Si,Ti) alloys. Also, the Ni–Si–Cr ternary alloys showed corrosion resistance comparable to the Ni 3Si and Ni 3(Si,Ti) alloys.