Load relaxation and creep behavior of a spray cast hypereutectic Al-25Si-2Cu-1Mg alloy

Abstract

We studied the high temperature deformation behavior of a spray cast Al-25Si-2Cu-1Mg alloy within the framework of an internal variable theory for inelastic deformation. We then carried out a series of load relaxation tests at elevated temperatures to obtain flow curves between flow stress and strain rate. The results were analyzed based on constitutive relations prescribed by an internal variable theory. The hypereutectic Al-25Si-2Cu-1Mg alloy exhibited two distinctly different deformation modes, viz. plastic deformation induced by dislocation glides and creep deformation by dislocation climbs at high temperatures. These load relaxation test results were then compared with those obtained from a series of creep tests performed at elevated temperatures under various stress levels. They were found to agree well with each other, providing a means to replace the time-consuming creep test by a simple load relaxation test in order to obtain high temperature creep data.