The temperature effect on forming gradient structure in an Al–Si alloy during surface severe deformation is studied in this report. The intermediate temperature (473 K) produces the steepest gradient structure by an anomalous hardening on the top layer compared to lower (300 K) and higher temperature (673 K) counterparts. Our analysis shows profuse aluminum oxide particles in the top layer of the gradient structure under 473 K lead to anomalous hardening by oxide-dispersion strengthening. The counterintuitive enhancement of strengthening at the intermediate temperature is explained by the dynamic interplay between thermal-driven, mechanical-aided oxidation and the wear-induced loss of surface materials as a function of temperature, which yields a critical processing temperature to achieve the steepest gradient structure.

本报告研究了表面剧烈变形过程中温度对 Al-Si 合金中梯度结构形成的影响。与较低温度 (300 K) 和较高温度 (673 K) 对应的温度相比，中间温度 (473 K) 通过顶层的异常硬化产生最陡峭的梯度结构。我们的分析表明，在 473 K 下梯度结构顶层中的大量氧化铝颗粒通过氧化物弥散强化导致异常硬化。中间温度下强化的违反直觉的增强可以通过热驱动、机械辅助氧化和磨损引起的表面材料损失之间的动态相互作用来解释，作为温度的函数，这产生了一个临界加工温度，以实现最陡的梯度结构体。