Abstract:
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
