In-Situ Investigation of Grain Boundary Mobility and Character in Aluminum Alloys in the Presence of a Stored Energy Driving Force

This paper investigates the effect of solute (namely Zr, Fe and Si) in Al alloys on grain boundary character and mobility based on experiments in which individual boundaries migrate under a stored energy driving pressure acquired from prior plastic strain. A compensation effect is noted both alloys studied with respect to both temperature and solute content. As supported by the literature, boundaries exhibit a maximum mobility for a 38-39o<111> misorientation in initial annealing experiments; this mobility maximum is asymmetric with a sharp cutoff below 38-39o but a more gradual decrease at misorientations beyond 40o. The presence of a minimum at 38-39o is found at both higher temperatures and higher solute concentrations. A shift in texture dependency with solute and temperature is also observed. This transition from a local mobility maximum to a minimum is discussed within the context of recent developments in solute drag theory.