Mg–3Nd–0.2Zn–0.4Zr (NZ30K, wt.%) alloy is a new kind of high-performance metallic biomaterial. The combination of the NZ30K Magnesium (Mg) alloy and selective laser melting (SLM) process seems to be an ideal solution to produce porous Mg degradable implants. However, the microstructure evolution and mechanical properties of the SLMed NZ30K Mg alloy were not yet studied systematically. Therefore, the fabrication defects, microstructure, and mechanical properties of the SLMed NZ30K alloy under different processing parameters were investigated. The results show that there are two types of fabrication defects in the SLMed NZ30K alloy, gas pores and unfused defects. With the increase of the laser energy density, the porosity sharply decreases to the minimum first and then slightly increases. The minimum porosity is 0.49 ± 0.18%. While the microstructure varies from the large grains with lamellar structure inside under low laser energy density, to the large grains with lamellar structure inside & the equiaxed grains & the columnar grains under middle laser energy density, and further to the fine equiaxed grains & the columnar grains under high laser energy density. The lamellar structure in the large grain is a newly observed microstructure for the NZ30K Mg alloy. Higher laser energy density leads to finer grains, which enhance all the yield strength (YS), ultimate tensile strength (UTS) and elongation, and the best comprehensive mechanical properties obtained are YS of 266 ± 2.1 MPa, UTS of 296 ± 5.2 MPa, with an elongation of 4.9 ± 0.68%. The SLMed NZ30K Mg alloy with a bimodal-grained structure consisting of fine equiaxed grains and coarser columnar grains has better elongation and a yield drop phenomenon.

中文翻译：

---

加工参数对选区激光熔化增材制造 Mg-Nd-Zn-Zr 合金制造缺陷、显微组织和力学性能的影响


Mg–3Nd–0.2Zn–0.4Zr (NZ30K, wt.%)合金是一种新型高性能金属生物材料。 NZ30K 镁 (Mg) 合金与选择性激光熔化 (SLM) 工艺的结合似乎是生产多孔镁可降解植入物的理想解决方案。然而，SLMed NZ30K 镁合金的显微组织演变和力学性能尚未得到系统研究。因此，研究了不同加工参数下SLMed NZ30K合金的制造缺陷、显微组织和力学性能。结果表明，SLMed NZ30K合金中存在两种类型的加工缺陷：气孔和未熔合缺陷。随着激光能量密度的增加，孔隙率先急剧下降至最小值，然后略有增加。最小孔隙率为0.49±0.18%。显微组织由低激光能量密度下的大颗粒内部层状结构，到中激光能量密度下的大颗粒内部层状结构及等轴晶和柱状晶，进一步发展为细小的等轴晶和柱状晶。高激光能量密度下的晶粒。大晶粒中的层状组织是NZ30K镁合金新观察到的显微组织。较高的激光能量密度导致晶粒更细，从而提高了屈服强度（YS）、极限抗拉强度（UTS）和伸长率，获得的最佳综合力学性能为YS为266±2.1 MPa，UTS为296±5.2 MPa，伸长率为4.9±0.68%。 SLMed NZ30K镁合金具有细等轴晶和粗柱状晶组成的双峰晶粒组织，具有较好的延伸率和屈服下降现象。