Hardness and Microstructure Changing of Fe-base Amorphous Alloy Coating during Crystallizing Process

A kind of FeB base amorphous alloy coating(contains Cr,Ni,W,Mo,C,Si) was fabricated by plasma spraying, and the coating was heattreated at different temperature(100~730℃) for 4h respectively The DSC test shows that the coating′s crystallizing temperature is about 590℃ The heat treatment results show that, when the heat treatment temperature is below 450℃,the coating is still amorphous structure, and the hardness changes a little When the heat treatment temperature is in the range of 450~610℃, the content of crystallizing phases increases gradually with the temperature improving, the crystallizing phases consist of Fe23(C,B)6, Fe23B6 and richFe phase, and the grain size of crystallizing phase is very small(that is about 20nm after 590℃4h heat treatment), so the hardness increases rapidly The hardness of the coating up to maximum value(about 1270HV) after 610℃4h heat treatment When the heat treatment temperature is in the range of 630~730℃,richFe phase becomes a primary microstructure,and the grain grows up to 5μm after 660℃4h heat treatment Although some Fe23(C,B)6,Fe23B6,Fe3B and FeB phase exist in the coating,the hardness decreases rapidly with the temperature increasing 