Structure and Properties of Fe-Ni-Al-Si Alloys Produced by Powder Metallurgy

Reactive sintering powder metallurgy is a simple alternative to conventional melting and powder metallurgy processes. During this process, pressed powder mixture of pure metals or other precursors is transformed into bulk intermediary phases by thermally activated in situ reaction. This process was previously tested on Fe Al and Fe Al Si alloys. Positive e ect of silicon on the reactive sintering behaviour was determined, leading to the development of novel carbon-free high-silicon FeAl20Si20 alloy (given in wt%). In this work, the e ect of nickel on the pressureless reactive sintering of Fe Al Si pressed powder mixtures was studied. To explain the nickel in uence, di erential thermal analysis was utilized. Microstructure, phase composition and porosity of the FeAl20Si20Nix (x = 0, 5, 10, 20 wt%) alloys was described. Hardness, wear resistance, high-temperature oxidation resistance and thermal stability were evaluated as functions of nickel content. Results showed that porosity decreases with growing nickel content down to less than 3 vol.%. Oxidation rate of these alloys is more than 10 times lower than that of original FeAl20Si20 alloy. Thermal stability and abrasive wear resistance of these alloys is also superior to Fe Al and Fe Al Si materials.