Mg-Y-Ni alloys with different second phases were designed by changing Y/Ni atomic ratio from 1.5 to 0.5. The microstructure and mechanical properties of as-cast and as-extruded alloys were investigated. The as-cast Mg-Y-Ni alloy with Y/Ni ratio of 1.5 is composed of α-Mg and long period stacking ordered (LPSO) phase. When Y/Ni ratio is equal to 1, nanoscale lamellar γ' phase and eutectic Mg₂Ni phase are formed in addition to LPSO phase. As Y/Ni ratio decreases further, the amount of eutectic Mg₂Ni phase increases, while the amount of LPSO phase decreases. After extrusion, the LPSO and γ' phases are distributed along the extrusion direction, while eutectic Mg₂Ni phase is broken and dispersed in the as-extruded alloys. LPSO phase and Mg₂Ni phase in the alloys promote dynamic recrystallization (DRX) during extrusion, while γ' phase inhibits DRX. Consequently, the Mg96Y2Ni2 (at.%) alloy with LPSO phase and γ' phase as the main second phases shows the strongest basal texture after extrusion. The tensile yield strength of the as-extruded Mg-Y-Ni alloys increases first and then decreases with decreasing Y/Ni ratio. The as-extruded Mg96Y2Ni2 (at.%) alloy with Y/Ni = 1 exhibits excellent mechanical properties with tensile yield strength of 465 MPa, ultimate tensile strength of 510 MPa and elongation to failure of 7.2%, which is attributed to the synergistic effect of bulk LPSO phase and nanoscale γ' phase.

通过将Y / Ni原子比从1.5更改为0.5来设计具有不同第二相的Mg-Y-Ni合金。研究了铸态和挤压态合金的显微组织和力学性能。Y / Ni比为1.5的Mg-Y-Ni铸态合金由α-Mg和长周期有序相（LPSO）相组成。当Y / Ni比等于1时，除了LPSO相之外，还形成了纳米级层状γ′相和低共熔Mg ₂ Ni相。随着Y / Ni比的进一步降低，共晶Mg ₂ Ni相的量增加，而LPSO相的量减少。挤压后，LPSO和γ'相沿挤压方向分布，而共晶Mg ₂ Ni相破碎并分散在刚挤压的合金中。LPSO相和Mg ₂合金中的Ni相促进挤压过程中的动态再结晶（DRX），而γ'相则抑制DRX。因此，以LPSO相和γ'相为主要第二相的Mg96Y2Ni2（at。％）合金在挤压后表现出最强的基础组织。挤压后的Mg-Y-Ni合金的拉伸屈服强度先增加，然后随着Y / Ni比的降低而降低。Y / Ni = 1的Mg96Y2Ni2（at。％）挤压态合金具有出色的机械性能，拉伸屈服强度为465 MPa，极限抗拉强度为510 MPa，断裂伸长率为7.2％，这归因于协同效应LPSO相和纳米级γ'相的分布。