This study investigates the in situ alloying of a Ni-based superalloy processed by means of laser powder bed fusion (LPBF). For this purpose, Inconel 625 powder is mixed with 1 wt.% of Ti6Al4V powder. The modified alloy is characterized by densification levels similar to the base alloy, with relative density superior to 99.8%. The material exhibits Ti-rich segregations along the melt pool contours. Moreover, Ti tends to be entrapped in the interdendritic areas during solidification in the as-built state. After heat treatments, the modified Inconel 625 version presents greater hardness and tensile strengths than the base alloy in the same heat-treated conditions. For the solution annealed state, this is mainly attributed to the elimination of the segregations into the interdendritic structures, thus triggering solute strengthening. Finally, for the aged state, the further increment of mechanical properties can be attributed to a more intense formation of phases than the base alloy, due to elevated precipitation strengthening ability under heat treatments. It is interesting to note how slight chemical composition modification can directly develop new alloys by the LPBF process.

中文翻译：

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通过激光粉末床熔融原位合金化改性 Inconel 625：微观结构和机械性能

本研究调查了通过激光粉末床熔化 (LPBF) 加工的镍基高温合金的原位合金化。为此，将 Inconel 625 粉末与 1 wt.% 的 Ti6Al4V 粉末混合。改性合金的特点是致密化水平与基础合金相似，相对密度优于99.8%。该材料沿熔池轮廓呈现出富钛偏析。此外，在竣工状态的凝固过程中，Ti 往往会被截留在枝晶间区域。热处理后，在相同热处理条件下，改良的 Inconel 625 版本比基础合金具有更高的硬度和抗拉强度。对于固溶退火状态，这主要归因于消除了进入枝晶间结构的偏析，从而引发了溶质强化。最后，对于时效状态，机械性能的进一步提高可归因于比基体合金更强烈的相形成，这是由于热处理下的析出强化能力提高。有趣的是，通过 LPBF 工艺，轻微的化学成分改变可以直接开发出新的合金。