Fabrication and wear properties of Fe₃Al-based composites

Microstructures and wear properties of a recycled Fe₃Al-based alloy made from high-carbon Cr steel sludge and Al can scraps were first investigated in this study. The alloy was composed of D0₃-type Fe₃Al matrix and Fe₃AlC_0.5 dispersions (κ phase). Carbon in the steel sludge and Al can scraps contributes to the formation of the K phase. Next, the recycled Fe₃Al-based composites reinforced by transition metal carbides (TMC = TiC, NbC, V₄C ₃, and ZrC) were fabricated by in-situ reactions between transition metals (TM = Ti, Nb, V, and Zr) and carbon when these transition metals are added to the molten Fe₃Al-based alloy. The (Fe, Al)₂Nb intermetallic compound and a Fe-Al-Zr-C carbide are also formed in the Nb- and Zr-added Fe₃Al-based composites with NbC and ZrC, respectively. The Vickers hardness values of the recycled Fe₃Al-based composites reinforced by TMC were higher than that reinforced only by the κ phase. Abrasive wear behavior is observed for these composites. The carbides of the κ phase, TiC, NbC, V₄C₃ and ZrC are still embedded in the matrix after abrasive wear without delamination or destruction. This result indicates that the carbides significantly affect the wear resistance of these composites. The wear resistance of the composites reinforced by TMCs is higher than that reinforced by the κ phase. Moreover, the wear resistance of the recycled Fe₃Al-based composites reinforced by TiC is much higher than that of gray cast iron; the former value is comparable to that of high-carbon Cr steels. Thus, carbon in the steel sludge and Al can scraps is useful to synthesize hard carbides with transition metals. We have succeeded in preparing the valuable recycled Fe₃Al-based composites with excellent wear resistance from the industrial steel and Al scraps.