Characterization of cyclic dynamic and creep responses of pure aluminum by instrumented indentation

Abstract

<p indent="0mm">Dynamic behavior under cyclic loading conditions and creep behavior under quasi-static loading conditions were investigated by instrumented indentation of pure aluminum to reveal the influence of loading conditions (e.g., load, loading rate, and holding time) on indentation responses. The results of cyclic indentation show that, with the increase in the holding time, load, and loading rate of the pre-cyclic loading segment, the effect of creep on the subsequent cyclic indentation can be weakened, and the measured mechanical properties (e.g., contact depth, indentation hardness, and elastic modulus) can reach constant levels more rapidly with the increase in cycle number. The results of the creep tests show that the elastic modulus and indentation hardness decrease with the increase in holding time, the steady-state creep stress exponent obtained by instrumented indentation is independent of load, and a long holding time is not suggested for the creep tests. Indentation hardness and steady-state creep resistance measured within the inner grains are higher than those measured near the grain boundary regions.