Bulk ultra-fine grained materials produced by severe plastic deformation often had low ductility. Here the authors report that simultaneous increases in ductility and strength could be achieved by tailoring the stacking-fault energy via alloying. Specifically, ultra-fine grained bronze (Cu-10wt%Zn) with a stacking-fault energy of 35mJ/m2 was found to have much higher strength and ductility than ultra-fine grained Cu with a stacking-fault energy of 78mJ/m2. Accumulations of both twins and dislocations during tensile testing played a significant role in enhancing the ductility of the ultra-fine grained bronze. This suggested a strategy for designing ultra-fine grained alloys having superior mechanical properties.

Tailoring Stacking Fault Energy for High Ductility and High Strength in Ultrafine Grained Cu and its Alloy. Y.H.Zhao, Y.T.Zhu, X.Z.Liao, Z.Horita, T.G.Langdon: Applied Physics Letters, 2006, 89[12], 121906