Research on the Microstructure and Performance of Plasma Transfer Arc Spray Welded Cobalt-based Alloy

The microstructure and microhardness of plasma arc spray welded Cobalt-based alloy were investingated using optical metalography,scanning electron microscope(SEM),X-ray diffraction(XRD)and microhardness testing.Meanwhile,the changing of phase and microhardness of the Cobalt-based alloy layer during aging was studied.The results showed that the Cobalt-based alloy layer was made up ofγ(Co)and (Cr,Fe) 7(C,B) 3,and the hypoeutectic structure was shown at the same time.On the other hand,the phase of the alloy layer changed during aging,and (Cr,Fe) 7(C,B) 3changed into Cr 23 (C,B) 6and the microhardness of the alloy increased about 11%.Research showde that the precipitation of new phase,the changing and the accumulation of the phase during aging were the reasons for the changing of microhardness of the spray welding layer.