Ultrasonic energy can promote the dislocation motion in ultrasonic-assisted machining. The phase redistribution of Ti-6Al-4V alloy will occur in ultrasonic-assisted machining with appropriate ultrasonic powers. The variations of the volume fractions of β-Ti and α-Ti influence the microhardness on the processed surface. In the present paper, various rotary ultrasonic roller burnishing experiments were conducted to investigate the ultrasonic-induced phase redistribution of Ti-6Al-4V at different ultrasonic powers. The volume fractions of β-Ti and α-Ti were measured by X-ray diffraction. SEM images of the processed surfaces were used to analyze the microstructure evolution and grain refinement of Ti-6Al-4V at various ultrasonic powers. Then, the distributions of local misorientation, texture and grain boundary were observed by EBSD. The results indicated that the microhardness approached the maximum value on the processed surface while the volume fraction of β-Ti reached its maximum value. Finally, the modified phenomenological model was applied to elucidate the relationship among the microhardness, the phase volume fractions and the grain refinement. The fitting degree for microhardness between the modified phenomenological model prediction and experimental measurement was 92.2 pct.

中文翻译：

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旋转超声辊抛光Ti-6Al-4V的超声诱导相重分布和声硬化

超声波能在超声辅助加工中促进位错运动。Ti-6Al-4V合金的相变会在具有适当超声功率的超声辅助加工中发生。β- Ti和α- Ti的体积分数的变化会影响加工表面的显微硬度。在本文中，进行了各种旋转超声辊抛光实验，以研究在不同超声功率下超声诱导的Ti-6Al-4V的相重新分布。β- Ti和α的体积分数-Ti通过X射线衍射测定。加工表面的SEM图像用于分析在不同超声功率下Ti-6Al-4V的组织演变和晶粒细化。然后，通过EBSD观察了局部取向不良，织构和晶界的分布。结果表明，在加工后的表面上，显微硬度接近最大值，而β- Ti的体积分数达到最大值。最后，应用改进的现象学模型阐明了显微硬度，相体积分数和晶粒细化之间的关系。改进的现象学模型预测与实验测量之间的显微硬度拟合度为92.2 pct。