ABSTRACT

The number of defects is the key indicator that affects the properties of the NiTi alloy fabricated by SLM and can be adjusted by the energy density. In this study, the NiTi alloy was manufactured by varying the laser power from 50 to 95 W and matching the scanning speed of 200 to 900 mm/s at the hatch spacing of 80 and 110 μm. The results showed that the energy density for manufacturing high relative density (~99.5%) NiTi alloy was related to the laser power and was in the range of 45 to 70 J/mm³. Such ‘optimal energy density’ gradually decreased with the laser power or hatch spacing increasing. The results of XRD and DSC revealed that when the NiTi alloy was fabricated with low laser power and small hatch spacing induced the shape memory characteristics of heat recovery prominent. Instead, when the NiTi alloy was manufactured with high laser power and large hatch spacing, it would be superelasticity.

摘要

缺陷数是影响 SLM 制造的 NiTi 合金性能的关键指标，可以通过能量密度进行调整。在这项研究中，NiTi 合金的制造方法是将激光功率从 50 W 改变到 95 W，并在 80 和 110 μm 的舱口间距下匹配 200 到 900 mm/s 的扫描速度。结果表明，制造高相对密度（~99.5%）NiTi合金的能量密度与激光功率有关，在45~70 J/mm ^{3范围内。}. 这种“最佳能量密度”随着激光功率或舱口间距的增加而逐渐降低。XRD和DSC结果表明，在低激光功率和小舱口间距制备NiTi合金时，热恢复的形状记忆特性突出。相反，当 NiTi 合金以高激光功率和大孵化间距制造时，它会是超弹性的。