Effect of Precipitation on the Microhardness Distribution of Diode Laser Epitaxially Deposited IN718 Alloy Coating

The microhardness distribution of the diode laser epitaxially deposited IN718 alloy coating was investigated. The Laves concentration in different regions of the coating was measured by binarization processing. The strengthening phase of the coating was characterized by transmission electron microscopy (TEM). The results showed that the microhardness increased along the depth of the coating. Part of Laves dissolved into austenitic matrix during the successive laser deposition. A little amount of strengthening phase was precipitated in the bottom region of the coating. It was attributed to the heat effect from the thermal cycle of successive deposition on the microstructure in the bottom region of the epitaxially deposited coating.