Multifunctional Materials, Materials Science and Technology Division, Naval Research Laboratory, Washington DC, 20375, USA.
Sci Rep. 2017 Aug 31;7(1):10179. doi: 10.1038/s41598-017-10889-8.
Stress-assisted grain growth at room temperature is known for materials with nanocrystalline grains. For larger grain sizes, the grain growth usually takes place at higher homologous temperatures even under stress. Here we report, for the first time, significant grain growth at room temperature under fatigue loading in microcrystalline grains (≥10 μm) in Al 7075. We demonstrate that this grain growth at room temperature is similar to non-uniform grain growth due to grain rotation and coalescence rather than the thermally and the stress-assisted driven grain growth. We show that the grain growth is associated with the formation of a strong near-Cu {112}<111> texture component as a result of fatigue-assisted deformation. These changes in microstructural features (viz., grain size, grain orientations and texture) are fundamentally important in understanding the cyclic crack induced deformation behavior and for predicting the fatigue lifetime in structural materials.
室温下的应力辅助晶粒长大已知存在于具有纳米晶颗粒的材料中。对于更大的晶粒尺寸，即使在应力下，晶粒生长通常也会在更高的同系温度下发生。在这里，我们首次报道了在 Al 7075 的微晶粒（≥10μm）中在疲劳载荷下室温下的显著晶粒长大。我们证明，这种室温下的晶粒长大类似于由于晶粒旋转和聚合并非由于热和应力辅助驱动的晶粒长大导致的不均匀晶粒长大。我们表明，晶粒生长与由于疲劳辅助变形而形成的强近-Cu{112}<111>织构组分有关。这些微观结构特征（即晶粒尺寸、晶粒取向和织构）的变化对于理解循环裂纹诱导的变形行为以及预测结构材料的疲劳寿命至关重要。
