Published online by Cambridge University Press: 10 February 2011
The Zr-Cr-Mn system is used to explore the effect of a lowered SFE on the room temperature mechanical properties of a Laves phase using elements of similar atomic size. The ternary Zr-Cr-Mn diagram in the region from 0 to 12 at. % Mn is first determined and it is shown that Mn substitutes only for Cr in the Laves phase. TEM analysis of the density of stacking fault energy related defects such as annealing twins indicates that Mn substitution for Cr in ZrCr2 lowers the SFE of the cubic Laves phase. Mechanical testing of the two phase alloys is used to explore the effects of Mn content and the volume fraction of each phase on the ductility and fracture behavior in compression. It is found that the mechanical properties are well-described by a model incorporating solid solution strengthening in a ductile-brittle two phase alloy.