The effect of stacking-fault energy on the evolution of microstructures during room-temperature tensile testing was investigated at strain rates of 8.3 x 10-4 and 1.7 x 10-1/s in pure copper, Cu-2.2%Al, and Cu-4.5%Al alloys having stacking-fault energies about 78, 20 and 4mJ/m2, respectively. The deformation mechanism changed from simple slip, leading to cell formation in the high stacking-fault energy metal, Cu, to overlapping and/or intersecting deformation twins in the low stacking-fault energy alloy, Cu-4.5%Al. The effect of strain rate was such that it resulted in rather poorly defined cell boundaries in copper, with a smaller cell size at higher strain rates for similar grain sizes and strain values. The alloys deformed by twinning, and the propensity to deformation twins increased with both a decrease in stacking-fault energy and an increase in strain rate.

Effect of Stacking Fault Energy and Strain Rate on the Microstructural Evolution during Room Temperature Tensile Testing in Cu and Cu-Al Dilute Alloys. V.Caballero, S.K.Varma: Journal of Materials Science, 1999, 34[3], 461-8