MICROSTRUCTURE OF Fe-Cr SURFACE INFILTRATED COMPOSITE LAYER ON GRAY IRON SUBSTRATE

The Fe-Cr surface infiltrated layers on gray iron substrate were fabricated through a vacuum infiltration casting technique (VICT) using Fe-Cr alloy powder as raw materials. The microstructures of surface infiltrated layer, the macro-hardness and the micro-hardness distribution are investigated. The infiltrated layer includes a surface composite layer and a transition layer. The surface infiltrated layer was mainly composed of Cr2B, Cr2C3, FeSi, FeNi and Ni-Cr-Fe and solid solution. The main composition of transition layer was graphite, eutectic ledeburite, carbide and Fe-based solid solution. The macro-hardness of surface infiltrated layer is HRC52.8, and the macro-hardness of substrate is HRC16.22. The distribution of micro-hardness presents gradient change.