Strength, ductility and fracture toughness are the most important mechanical properties of engineering materials. In this work, an Al–Zn–Mg–Cu alloy was subjected to multi-directional forging (MF) and ageing treatment. Microstructural evolution was studied by optical and electron microscopy and strength, ductility and fracture toughness were researched. After MF, the dislocation density was increased and the microstructure was refined. The strength and fracture toughness were increased, while the ductility was decreased sharply. Without compromising the strength, the ductility was improved significantly after ageing. The fracture toughness was increased further. The coarse and discontinuously distributed grain boundary precipitates were found to be responsible for higher fracture toughness of the fine-grained structure Al–Zn–Mg–Cu alloy.

中文翻译：

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多向锻造和时效对Al-Zn-Mg-Cu合金断裂韧性的影响

强度、延展性和断裂韧性是工程材料最重要的力学性能。在这项工作中，Al-Zn-Mg-Cu 合金经过多向锻造 (MF) 和时效处理。通过光学和电子显微镜研究了显微组织演变，并研究了强度、延展性和断裂韧性。MF后，位错密度增加，显微组织细化。强度和断裂韧性增加，而延展性急剧下降。在不影响强度的情况下，时效后延展性显着提高。断裂韧性进一步提高。发现粗大且不连续分布的晶界析出物是细晶结构 Al-Zn-Mg-Cu 合金断裂韧性较高的原因。