Development of Fe-20Cr-5Al-1Y2O3 ODS alloy with addition of Ni by means of Arc plasma sintering (APS) method

Abstract

APS has two main advantages over the conventional method since it reduces the energy consumption and process time significantly. In this work, ODS alloys composed of Fe-20Cr-5Al-1Y2O3 with addition of 0.5, 1, 1.5, and 2 wt% nickel were produced. These alloys are firstly fabricated via powder metallurgy method consisting of mechanical alloying by high energy milling for 8 hours and uniaxial isostatic pressing with 20 ton-force/in2 pressure, and subsequent sintering in APS for 28 minutes. The alloy samples were investigated using Scanning Electron Microscope (SEM) equipped with X-Ray Diffraction Spectroscopy (EDX) to reveal the microstructure and chemical composition, X-Ray Diffraction (XRD) to analyze the phases which occur after sintering, and Vickers micro hardness testing to examine the hardness value of specimens. The results show that APS method in processing ODS alloy has given two main technical advantages over the conventional method: first, low energy need, and second, short process time. The addition of nickel leads to the formation of the microstructure consisting of three main phases, the (Fe,Ni) or kamacite, NiAl and ferrite matrix. The presence of NiAl is recognized as essential since it can improve oxide particles within the alloy matrix and along grain boundaries to impede dislocation motion particularly at high temperature (creep). Nickel addition also shows increasing hardness value of the ODS alloys.