Abstract Nanocrystalline Ti/AZ61 magnesium matrix composite, prepared by mechanical milling, was annealed in the temperature range of 573–723 K for various durations. During annealing treatment, diffusion of Al and Ti elements, formation of precipitates and grain growth behavior were observed and the evolution of hardness was obtained. Based on microstructural evolution, the mechanism for the precipitating of Ti and Al from magnesium matrix was analyzed. And the corresponding schematic illustration of microstructural evolution model was proposed. By the observation from high-resolution transmission electron microscopy, it was found that dispersing nanometer sized particulates, precipitated from Ti and Al supersaturated Mg solid solution, pined up magnesium grain boundaries. During annealing treatment, the nano-scaled precipitates together with original submicron Ti particulates hindered the movement of grain boundaries. Thus, the thermal stability for magnesium grains was improved. After annealing treatment at 723 K for 600 min, this magnesium matrix composite with the average grain size of ∼93 nm was still nanocrystalline. In addition, influence of temperature and time on hardness was investigated. After annealing treatment at 723 K for 600 min, the hardness of annealed Ti/AZ61 composite is approximately 116 HV, presenting outstanding thermal stability.

中文翻译：

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纳米晶 Ti/AZ61 镁基复合材料：退火处理过程中微观结构和力学性能的演变

摘要 通过机械研磨制备的纳米晶 Ti/AZ61 镁基复合材料在 573-723 K 的温度范围内退火不同时间。在退火处理过程中，观察到Al和Ti元素的扩散、析出物的形成和晶粒长大行为，并获得了硬度的演变。基于显微组织演化，分析了钛和铝从镁基体中析出的机理。并给出了相应的微观结构演化模型示意图。通过高分辨率透射电子显微镜观察，发现从Ti和Al过饱和Mg固溶体中析出的分散的纳米尺寸的颗粒固定了镁的晶界。在退火处理过程中，纳米级沉淀物与原始亚微米钛颗粒一起阻碍了晶界的运动。因此，改善了镁晶粒的热稳定性。在 723 K 下退火处理 600 分钟后，这种平均晶粒尺寸约为 93 nm 的镁基复合材料仍然是纳米晶。此外，还研究了温度和时间对硬度的影响。在723 K 600 min 退火处理后，退火后的Ti/AZ61 复合材料的硬度约为116 HV，表现出优异的热稳定性。研究了温度和时间对硬度的影响。在723 K 600 min 退火处理后，退火后的Ti/AZ61 复合材料的硬度约为116 HV，表现出优异的热稳定性。研究了温度和时间对硬度的影响。在723 K 600 min 退火处理后，退火后的Ti/AZ61 复合材料的硬度约为116 HV，表现出优异的热稳定性。