基于 增 材 制造 的 原 位 合金 化 制 造方 法 的 研 究进 展

In situ alloying based on additive manufacturing of blends of several kinds of elemental or alloyed powders is a low cost, rapid and efficient method to develop new materials, which has been preliminarily applied in the fields of high entropy alloy development, new biomedical alloy printing development and so on. In this paper, the effects of powder morphology, particle size, high melting point powder content, powder mixing technology on the performance of in situ alloying printed samples are introduced. The results show that in order to ensure the in situ alloying printing effect, the particle gradation of mixed powder should ensure both the element mixing uniformity and the powder fluidity. The printing technology including laser power, beam spot diameter and remelting strategy also influences the geometry of the melting pools, which in turn, affect the in situ alloying process. The greater the pool depth, the more guarantee the interlayer remelting in the printing process, promote the element uniformity, but too deep pool will cause pores. The study of alloys with composition fluctuation or gradient based on in situ alloying printing is also introduced. It has been shown that the inhomogeneity of composition which is inherent in the in situ alloying process facilitates the preparation of alloys with inhomogeneous composition, resulting in bi-phasic additive printing, which cannot be obtained by printing based on pre-alloy powders. Based on the multi material and multiphase flow model, the numerical model of laser melting process of in situ alloying has also been established. The numerical simulation of laser powder bed fusion based on in situ alloying shown that the optimized in situ alloying process was different from that of laser powder bed fusion based on pre-alloyed powder. Finally, the application prospect and challenges of in situ alloying technology based on additive manufacturing are prospected.