Laser cladding of stainless steel on magnesium ZK60/SiC composite

Laser cladding of stainless steel on ZK60/SiC composite was achieved by using a two-step method, i.e. thermal spray and laser re-melting. This was made possible by using interlayers of brass and copper, as a result, good metallurgical bond interfaces were obtained. However, the rapid solidification condition caused liquid phase separation. As a consequence, small spheroids of copper-rich phase were formed in the stainless steel matrix, which are found to be detrimental to the corrosion resistance of the material. Nonetheless, the corrosion potential (Ecorr) of the laser-cladded sample was 1090 and 820 mV higher than that of the as-received and as-sprayed samples, respectively, while the corrosion current (icorr) was some two and four orders of magnitude lower. The laser-cladded sample, like the untreated composite, did not show a passive region in the polarization plot. This is believed to be due to the segregation of copper-rich phase at interdendritic regions, and the presence of copper-rich spheroids in the stainless steel matrix.