WT10.BZ>Laser surface melting (LSM) modified layers on cast AlSi alloy were obtained using a CO_2 continuous transverse flow
laser beam with maximum power of 10kW The
microstructure of LSM modified layers were studied by using optical microscope, scanning electron microscope(SEM) and energy dispersive spectroscope(EDS), transmission electron microscope(TEM) and Xray
diffraction (XRD)It is shown that LSM modified layer could be divided in cellular, dendritic and mixed crystal zones The grain size of LSM modified layers became much finer than that of substrate material The results of Xray diffraction(XRD) and selected area diffraction(SAD) analysis indicated that much more silicon atoms were saturated in crystalline cells of αAl phase through LSM processing Microhardness distribution from surface to substrate on cross section plane was also tested The average microhardness of LSM modified layers were in the range from 116 to 203HV, and wear resistance was enhanced greatly Generally, improvement of mechanical property was due to the effects of finegrained microstructure and oversaturated αAl crystalline in LSM modified layers