Microstructure evolution and mechanical properties of a high-strength Mg-10Gd-3Y-1Zn-0.4Zr alloy fabricated by laser powder bed fusion
Microstructure evolution and mechanical properties of a high-strength Mg-10Gd-3Y-1Zn-0.4Zr alloy fabricated by laser powder bed fusion
复制标题
激光粉末床熔合高强Mg-10Gd-3Y·1Zn-0.4Zr合金的组织演变及力学性能
DOI：
10.1016/j.addma.2021.102517
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发表时间：
2022-01-01
影响因子：
11
通讯作者：
Ding, Wenjiang
中科院分区：
文献类型：
--
作者：
Deng, Qingchen;Wu, Yujuan;Ding, Wenjiang
采用激光粉末床熔融（LPBF）技术制备了一种高强度Mg - 10Gd - 3Y - 1Zn - 0.4Zr（GWZ1031K，质量分数）合金，并系统研究了其原始态、LPBF - T5态、LPBF - T4态和LPBF - T6态的微观结构和力学性能。原始态合金由平均晶粒尺寸为4.1±0.5μm的细小等轴α - Mg晶粒、网状β - (Mg,Zn)₃(Gd,Y)共晶相和片状Y₂O₃氧化物相组成，其屈服强度（YS）为310±8 MPa，极限抗拉强度（UTS）为347±6 MPa，伸长率（EL）为4.1±0.8%。LPBF后在175℃下进行64 h的简单直接时效热处理，使得LPBF - T5合金具有365±12 MPa的超高屈服强度，但伸长率较低，为0.8±0.3%。固溶热处理通过将硬而脆的共晶相转变为晶粒内部相对较软且可变形的层状长周期堆垛有序（LPSO）结构以及晶界处的X相，在无明显晶粒长大的情况下提高了塑性。此外，在450℃下固溶处理12 h的LPBF - T4合金的屈服强度为255±8 MPa，极限抗拉强度为328±9 MPa，伸长率为10.3±0.5%。固溶后的时效热处理引入了大量的棱柱形β′和β₁析出相，有助于提高抗拉强度。LPBF - T6合金的屈服强度、极限抗拉强度和伸长率分别为316±5 MPa、400±7 MPa和2.2±0.3%。可以得出结论，LPBF工艺与专门设计的后处理相结合，对于制造具有更高屈服强度的镁 - 稀土合金高性能部件以用于各种应用具有很大的前景。
A high-strength Mg-10Gd-3Y-1Zn-0.4Zr (GWZ1031K, wt%) alloy was prepared by laser powder bed fusion (LPBF), and the microstructure and mechanical properties of the as built, LPBF-T5, LPBF-T4, and LPBF-T6 states were systematically studied. The as built alloy is composed of fine equiaxed alpha-Mg grains with an average grain size of 4.1 +/- 0.5 mu m, reticular beta-(Mg,Zn)(3) (Gd,Y) eutectic phase and flaky Y2O3 oxide phase, and exhibits yield strength (YS) of 310 +/- 8 MPa, ultimate tensile strength (UTS) of 347 +/- 6 MPa and elongation (EL) of 4.1 +/- 0.8%. A simple direct aging heat treatment at 175 degrees C for 64 h after LPBF leads to an ultra-high YS of 365 +/- 12 MPa but a low EL of 0.8 +/- 0.3% in the LPBF-T5 alloy. The solution heat treatment improves ductility by transforming the hard and brittle eutectic phase into the relatively soft and deformable lamellar long period stacking ordered (LPSO) structure inside grains and X phase at grain boundaries without obvious grain growth. Moreover, the LPBF-T4 alloy solution-treated at 450 degrees C for 12 h exhibits YS of 255 +/- 8 MPa, UTS of 328 +/- 9 MPa, and EL of 10.3 +/- 0.5%. Aging heat treatment after solution introduces numerous prismatic beta' and beta(1) precipitates, which help to increase tensile strength. The YS, UTS, and EL of the LPBF-T6 alloy are 316 +/- 5 MPa, 400 +/- 7 MPa, and 2.2 +/- 0.3%, respectively. It can be concluded that the LPBF process when combined with specially designed post-processing holds great promise for the manufacturing of high-performance components of the Mg-rare earth alloys with significantly higher YS for various applications.