This study aims to investigate the extrusion temperature effects on the development of heterogeneous microstructures and mechanical properties, focusing on their impact on the fracture toughness of AZ31B alloys. Magnesium AZ31B (Mg-3wt%Al-1wt%Zn) alloys with high strength and reasonable fracture toughness, featuring heterogeneous microstructures, were fabricated via warm/hot extrusion at temperatures ranging from 523 to 723 K. The AZ31B alloy extruded at 523 K was bimodally grained into coarse worked grains with high Kernel average misorientation (KAM) values and fine dynamically recrystallized (DRXed) grains (< 10 µm) with intermediate KAM values. The 523 K-extruded alloy exhibited a high tensile yield strength of ∼280 MPa and fracture toughness K_JIC of ∼26 MPa·m^1/2. Conversely, the 723 K-extruded AZ31B alloy was trimodally grained into a small amount of worked grains, fine DRXed grains, and coarse DRXed grains (> 10 µm) with low KAM values. The 723 K-extruded alloy exhibited low tensile yield strength but a high K_JIC value of ∼36 MPa·m^1/2 owing to the high energy dissipation for crack extension in the coarse DRXed grains.

中文翻译：

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异质微观组织演变对挤压 AZ31B 合金拉伸韧性和断裂韧性性能的影响


本研究旨在研究挤压温度对异质微观组织和机械性能发展的影响，重点关注它们对 AZ31B 合金断裂韧性的影响。在 523 至 723 K 的温度范围内，通过温/热挤压制备了具有高强度和合理断裂韧性的镁 AZ31B （Mg-3wt%Al-1wt%Zn） 合金，具有异质微观结构。在 523 K 下挤压的 AZ31B 合金被双峰晶粒化成具有高内核平均取向差 （KAM） 值的粗加工晶粒和具有中等 KAM 值的细动态再结晶 （DRXed） 晶粒 （< 10 μm）。523 K 挤压合金表现出 ∼280 MPa 的高拉伸屈服强度和 ∼26 MPa·m^1/2 的断裂韧性 K_JIC。相反，723 K 挤压的 AZ31B 合金被三峰晶粒化为少量加工晶粒、细 DRXed 晶粒和低 KAM 值的粗 DRXed 晶粒 （> 10 μm）。723 K 挤压合金表现出较低的拉伸屈服强度，但由于粗 DRXed 晶粒中裂纹扩展的能量耗散很高，因此 K_JIC 值高达 ∼36 MPa·m^1/2。