Dual-phase Ni₃Al-based alloys feature extensive applicability even under high-temperature conditions. We selectively modified the microstructure of a representative dual-phase Ni₃Al-based alloy from equi-axed grains to unidirectional grains, using a kW-class high-power laser irradiation technique. On employing the laser probe to linearly scan the Ni-9 at.% Al-16 at.% V alloy specimen, the laser-irradiated region was partially molten and then immediately solidified from the two edges of the molten pool toward the center. Laser irradiation under low-speed scanning increased the molten pool width. The grains in the laser-irradiated region extended preferentially from the two edges toward the center; their crystal orientation was similar to adjacent substrate grains, suggesting epitaxial growth. Therefore, the unidirectional orientation of grains could be extended via wide-range scanning using laser irradiation. This suggests that the microstructure of the alloy can be selectively modified to unidirectional orientated grains by optimizing laser irradiation conditions, such as the power density, scanning speed, and scanning paths. The hardness of the laser-irradiated region decreased due to the phase transformation from the ordered Ni₃Al and Ni₃V phases to the disordered fcc phase. However, the hardness improved to a value comparable to that of the alloy subjected to heat treatment at 980 °C for 1 h.

中文翻译：

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激光辐照Ni3Al基双相合金的单向晶体取向

Ni ₃ Al双相合金即使在高温条件下也具有广泛的适用性。我们有选择地修改了具有代表性的双相Ni ₃的微观结构使用kW级大功率激光辐照技术，将铝基合金从等轴晶粒转变为单向晶粒。在使用激光探针线性扫描Ni-9 at。％Al-16 at。％V合金样品时，激光辐照区部分熔化，然后立即从熔池的两个​​边缘向中心凝固。低速扫描下的激光照射增加了熔池宽度。激光辐照区域中的晶粒优先从两个边缘向中心延伸。它们的晶体取向类似于相邻的基底晶粒，表明外延生长。因此，可以通过使用激光照射的宽范围扫描来扩展晶粒的单向取向。这表明可以通过优化激光辐照条件（例如功率密度，扫描速度和扫描路径），将合金的微观结构选择性地修饰为单向晶粒。激光照射区域的硬度由于有序Ni的相变而降低₃ Al和Ni ₃ V相变为无序fcc相。但是，硬度提高到与在980℃下热处理1小时的合金相当的值。