Microstructure and thermal stability of MoSi2-CoNiCrAlY nanocomposite feedstock prepared by high energy ball milling

MoSi2-CoNiCrAlY nanocomposite feedstock was prepared by high energy ball milling starting from a mixture of 50 wt.% MoSi2 and 50 wt.% CoNiCrAlY powders. The microstructure and thermal stability were studied by means of scanning electron microscope (SEM), X-ray diffraction (XRD), laser particle size analyzer and differential scanning calorimeter (DSC). The results show that only grain refinement occurs in MoSi2-CoNiCrAlY powders during the whole milling process. The milled powders have nanocrystalline structure composed of nano-sized hard MoSi2 phase uniformly dispersed in CoNiCrAlY binder phase matrix. After milling for 30 h, both the average particle size and grain size of the powders are almost stabilized. The prepared nano-composite feedstock exhibits spherical morphology, uniform particle size and good thermal stability, which is expected to be used directly for thermal spraying hard coating after sieving slightly.