Triaxial Compression on Semi-solid Alloys

Multi-axial compression of the mushy zone occurs in various pressurized casting processes. Here, we present a drained triaxial compression apparatus for semi-solid alloys that allow liquid to be drawn into or expelled from the sample in response to isotropic or triaxial compression. The rig is used to measure the pressure-dependent flow stress and volumetric response during isothermal triaxial compression of globular semi-solid Al-15 wt pct Cu at 70 to 85 vol pct solid. Analysis of the stress paths and the stress–volume data show that the combination of the solid fraction and mean effective pressure determines whether the material undergoes shear-induced dilation or contraction. The results are compared with the critical state soil mechanics (CSSM) framework and the similarities and differences in behavior between equiaxed semi-solid alloys and soils are discussed.