Due to the formation of protective borosilicate scale during high-temperature oxidation, Mo-62Si-5B (at.%) alloy is deemed to be the promising candidate of high-temperature oxidation resistant coatings. Nevertheless, it faces the challenges on the application on surface engineering due to the difficulty of powder fabrication. In the present study, the pre-alloyed powder was obtained by mechanical crushing from Mo-62Si-5B bulk alloy fabricated by vacuum induction levitation melting. Subsequently, the original powder was further sieved by 60 mech sifter for the compatibility of laser cladding. The size distribution, morphology, oxygen content and phase composition of the powder were characterized. The results show that the D(50) of the powder is 130.55 μm and the average particle size is 124.65 μm. There are MoSi2 and MoB2 phases distributed in the powder with irregular morphologies, which is accord with the bulk Mo-62Si-5B alloy. The oxygen content of the powder is lower than 0.11%, meeting the requirements of the powder for laser cladding. A laser cladded layer was prepared on Nb-Si based alloy substrate by using the powders, which exhibits dense structure free of voids and cracks. The study proves the feasibility of pre-alloyed Mo-62Si-5B powder, which may give guidance for producing Mo-Si-B system oxidation-resistant coating by laser cladding or thermal spraying.
With the development of additive manufacturing technology, it provides an efficient method for preparing complex structured NiTi alloy specimens. Different additive manufacturing technologies have different requirements for powder particle size. In order to satisfy the requirements of additive manufacturing technology for powders. This study aimed to produce spherical NiTi powders suitable for additive manufacturing by electrode induction melting gas atomization (EIGA). Scanning electron microscopy, X-ray diffractometry and differential scanning calorimetry were used to investigate the surface and inner micro-morphology, phase constituent and martensitic transformation temperature of the surface and inner of the NiTi powders with different particle sizes. The results show that the powder mean particle size D50 was 75 μm, flowability was 19.3 s/50 g, apparent density was 3.40 g·cm–3, and the oxygen content of the powder only 0.005% higher than the raw materials. That the grain of powder becomes finer gradually with decreasing particle size. Ingot and all the powders exhibit a main B2 phase. Particles with different particle sizes have experienced different cooling rates during atomization. Various cooling rates cause different grain size inside the powder; in particular, the transformation temperature decreases with decreasing particle size. This study provides a basis for preparing high quality AM NiTi parts.
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