Abstract

The microstructural evolution of Mg–2.0Gd–1.2Y–1.0Zn–0.2Zr (GWZK) alloy during homogenization and subsequent aging heat-treatment and the tensile properties of the peak-aged sample at various temperatures have been investigated. The phase transformation during homogenization, static precipitation during aging, and deformation mechanisms at 250 °C are systematically analyzed through XRD, TEM and EBSD measurements. The peak-aged GWZK alloy has good combination of strength and ductility at elevated temperatures owing to its high thermal stability by the LPSO phases distributed along the grain boundaries. The change (19 MPa) in the yield strength of peak-aged samples between RT and 250 °C is mainly related to easy gliding of dislocations on the non-basal planes due to the decrease in critical resolved shear stress of slip. Two strengthening models are applied to quantitatively describe the effect of \({\left\{11\stackrel{-}{2}0\right\}}_{\alpha }\) precipitate plates on Orowan strengthening corresponding to RT and 250 °C. Ignoring changes in solid solution strengthening and grain boundary strengthening of the peak-aged sample caused by increasing temperature, the calculated reduction value (16.5 MPa) in macroscopic yield strength from RT (based on the basal < a > slip mode) to 250 °C (based on the pyramidal < c + a > slip mode) is in good agreement with the measured reduction value (19 MPa).

Graphic Abstract

中文翻译：

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Mg–2.0Gd–1.2Y–1.0Zn–0.2Zr合金的组织和力学性能

摘要

研究了Mg–2.0Gd–1.2Y–1.0Zn–0.2Zr（GWZK）合金在均质化和随后的时效热处理过程中的微观组织演变，以及在不同温度下峰值时效样品的拉伸性能。通过XRD，TEM和EBSD测量系统地分析了均质化过程中的相变，老化过程中的静态沉淀以及250°C时的变形机理。峰值时效GWZK合金由于沿晶界分布的LPSO相具有很高的热稳定性，因此在高温下具有良好的强度和延展性。在室温和250°C之间，峰值时效样品的屈服强度的变化（19 MPa）主要与滑移的临界解析剪切应力的减小有关，从而易于在非基面上滑动位错。\（{\ left \ {11 \ stackrel {-} {2} 0 \ right \}} _ {\ alpha} \）沉淀板在Orowan强化处，对应于RT和250°C。忽略由于温度升高而导致的峰值时效样品固溶强化和晶界强化的变化，计算得出的从RT（基于基<a>滑移模量）到250°C的宏观屈服强度的降低值（16.5 MPa） （基于金字塔<c + a>滑模）与实测压下值（19 MPa）非常吻合。

图形摘要