Ternary Mg₉₄Ni₂Y₄ (at%) alloy was prepared by conventional gravity casting or direct squeezing casting and then subjected to T6 heat treatment. The influence of squeeze casting pressure and heat treatment on microstructure evolution and mechanical properties of Mg₉₄Ni₂Y₄ alloy containing long period stacking ordered (LPSO) structure was studied. The results show that gravity cast Mg₉₄Ni₂Y₄ alloy consisted of primary α-Mg, 18 R LPSO and eutectic structure containing α-Mg, LPSO and Mg₂Ni phases. The application of pressure cannot change phase constituents and the type of LPSO phase. With the increase of squeeze casting pressure, microstructure was refined, the volume fraction of LPSO was decreased while that of eutectic structure was increased. Under the highest pressure of 320 MPa, kinking of LPSO phase was induced and the best mechanical properties were obtained, with the ultimate tensile strength of 250 MPa, the yield strength of 140 MPa and the elongation of 8%. They were improved by 20.2%, 22.8% and 45.5%, respectively, than those of gravity cast Mg₉₄Ni₂Y₄. After heat treatment, bulk-shaped LPSO phase transformed into rod-shaped one, but no lamellar 14 H LPSO was precipitated in the matrix. Besides, the application of squeeze casting pressure prevented LPSO from delaminating during heat treatment.

通过常规重力铸造或直接挤压铸造制备三元Mg ₉₄ Ni ₂ Y ₄（at％）合金，然后进行T6热处理。研究了挤压铸造压力和热处理对含长周期堆积有序（LPSO）结构的Mg ₉₄ Ni ₂ Y ₄合金的组织演变和力学性能的影响。结果表明，重力铸造Mg ₉₄ Ni ₂ Y ₄合金由初生α-Mg，18 R LPSO和含α-Mg，LPSO和Mg _2的共晶组织组成。镍相。施加压力不能改变相组成和LPSO相的类型。随着挤压铸造压力的增加，组织细化，LPSO的体积分数降低，而共晶组织的体积分数增加。在320 MPa的最高压力下，诱发了LPSO相的扭结，获得了最佳的力学性能，极限抗拉强度为250 MPa，屈服强度为140 MPa，伸长率为8％。与重力铸造的Mg ₉₄ Ni ₂ Y ₄相比，它们分别提高了20.2％，22.8％和45.5％。。热处理后，块状LPSO相转变为棒状一相，但在基体中没有沉淀出层状的14 H LPSO。此外，挤压铸造压力的施加防止了LPSO在热处理过程中分层。