Microstructure evolution and mechanical properties of Mg-LPSO two phase Mg96Y2Ni2 (at. %) alloy processed by hot extrusion and decreasing-temperature ECAP
Microstructure evolution and mechanical properties of Mg-LPSO two phase Mg96Y2Ni2 (at. %) alloy processed by hot extrusion and decreasing-temperature ECAP
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DOI：
10.1016/j.matchar.2022.112552
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发表时间：
2023-01
影响因子：
4.7
通讯作者：
S.Z. Wu;Y. Chi;G. Garcés;X. Qiao;M. Y. Zheng
中科院分区：
文献类型：
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作者：
S.Z. Wu;Y. Chi;G. Garcés;X. Qiao;M. Y. Zheng
Mg96Y2Ni2(。通过挤压和随后的等通道角挤压（ECAP）处理含有长周期有序堆积（LPSO）相体积分数约50%的%)合金。通过调节挤压和ECAP工艺参数，得到了不同非动态再结晶比例的双峰α-Mg基体和不同晶粒尺寸的完全动态再结晶（DRXed）基体，并研究了拉伸性能与微观组织的关系。在390℃下挤压的合金，非DRXed区域面积比高（~ 35%），DRXed区域面积比低（~ 15%），DRXed晶粒细（~ 0.6 μm），具有505 MPa的超高抗拉屈服强度和3.5%的低断裂伸长率。在450°C下挤压的合金表现出双峰组织，其中非DRXed晶粒占~ 13%，DRXed晶粒占~ 37%，DRXed晶粒尺寸为2.1 μm，抗拉屈服强度为400 MPa，断裂伸长率为10%。挤压合金经400℃8道次和300℃4道次的ECAP处理后，得到了尺寸为~ 0.55 μm的完全再结晶的超细α-Mg晶粒。超细晶eced合金的抗拉屈服强度为450 MPa，断裂伸长率为8%，具有良好的强度-塑性平衡。与390°C挤压合金相比，eced合金的TYS较低可能是由于LPSO相断裂成颗粒，其传递载荷的效果不如长条，以及完全DRXed的晶粒，其织构较弱，强化效果不如非DRXed的基体织构强。而充分再结晶的超细Mg晶粒则有助于提高断裂伸长率。本研究为开发具有优异强度-延性协同性能的Mg-LPSO两相合金提供了理论指导。
The Mg96Y2Ni2(at. %) alloy containing ∼50% volume fraction of long period stacking ordered (LPSO) phase was processed by extrusion and subsequent equal channel angular pressing (ECAP). A bimodal α-Mg matrix with different non-dynamic recrystallized (non-DRXed) proportions and a fully dynamic recrystallized (DRXed) matrix with different grain sizes were obtained by regulating extrusion and ECAP processing parameters, and the relationship between tensile properties and microstructure was investigated. The alloy extruded at 390 °C has high area ratio of non-DRXed regions with ∼35% and low area ratio of DRXed regions with ∼15%, as well as fine DRXed grains of ∼0.6 μm, exhibiting ultrahigh tensile yield strength of 505 MPa and low elongation to failure of 3.5%. The alloy extruded at 450 °C exhibited bimodal microstructures containing non-DRXed grains with ∼13% and DRXed grains with ∼37%, and DRXed grains with the size of 2.1 μm, exhibiting tensile yield strength of 400 MPa and elongation to failure of 10%. Fully recrystallized ultra-fine α-Mg grains with the size of ∼0.55 μm was obtained after extrusion alloy was subjected to ECAP for 8 passes at 400 °C and subsequent 4 passes at 300 °C. The ultrafine-grained ECAPed alloy obtains tensile yield strength of 450 MPa and elongation to failure of 8%, exhibiting excellent strength-ductility balance. The lower TYS of the ECAPed alloy compared with the alloy extruded at 390 °C may be ascribed to the break of the LPSO phase into particles, which do not transfer load as effectively as long strips, as well as the fully DRXed grains with weak texture, which has less strengthening effect than that of the non-DRXed grains with strong basal texture. While the fully recrystallized ultra-fine Mg grains contribute to the increase of elongation to failure. This work provides theoretical guidance for develop of Mg-LPSO two-phase alloys with excellent strength-ductility synergy.