(Fe,Cr)7C3/Fe surface gradient composite: Microstructure, microhardness, and wear resistance

In this study, the (Fe,Cr)(7)C-3/Fe surface gradient composite was produced by in situ synthesis process with subsequent heat treatment. According to the results of thermal analysis, the as-cast specimen was subjected to heat treatment at 1180 degrees C for 3 h in argon atmosphere. The phase composition, microstructure, microhardness, and wear resistance of the samples were analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM), Vickers hardness tester, and wear resistance tester, respectively. The XRD results show that alpha-Fe and (Fe,Cr)(7)C-3 are the predominant crystalline phases in the composite obtained. The volume fraction of (Fe,Cr)(7)C-3 particulates has a gradient distribution from the surface to the matrix, and the morphology of (Fe,Cr)(7)C-3 particulates changes considerably. A dense ceramic layer is formed on the upper surface of (Fe,Cr)(7)C-3/Fe surface gradient composite with a volume fraction of 90%. The microhardness of the dense ceramic layer is 1484 HV0.1, and its relative wear resistance is five times higher than that of the iron matrix. (C) 2014 Elsevier B.V. All rights reserved.