摘要
TiCx-NiTi2/Ti cermet composite coatings C1 and C2 with gradient TiCx reinforcements were prepared on TC4 titanium alloy by laser cladding method.The microstructure and phase compositions were analyzed by means of scanning electron microscopy(SEM),energy-dispersive spectroscopy(EDS)and X-ray diffraction(XRD)meter.The TiCx exhibited a dendritic microstructure,and homogeneously dispersed in the Ti-based matrix where NiTi2 was embedded.With increasing ingredient supercooling,temperature gradient and cooling temperature,the dendrites displayed a finer morphology with longer primary trunks and intensified side branches in the dilution zone.But the smoothed,coarse columnar ones became dominant in the upper clad layer due to the repeated energy input during multi-track cladding.The Vickers microhardness presented a linear change trend through the cross-sections,which well confirmed the gradient distribution of TiCx.With more TiCx,C1 presented higher hardness than C2.
基金
supported by the National Key Technology Research and Development Program of the Ministry of Science and Technology of China(Grant No.2011BAE12B03)
the National Natural Science Foundation of China(Grant No.11372110)
