Macrostructures and shape memory effect of cast-state electropulse modified Cu-Al-Ni alloys

The electropulse modification (EPM) technique is used for the fabrication of CuAlNi shape memory polycrystalline alloy in order to improve the microstructure and to refine the grain-size. The macrostructure analysis on the unmodified and modified ingots was made, and the relevant shape memory effects of unmodified and modified ingots were tested. The grain-size of polycrystalline CuAlNi alloys is significantly reduced by EPM and the macrostructure is improved distinctly. A nearly full equiaxed region of the ingot is obtained and the corresponding concentrated shrink is reduced. The EPM voltage, frequency, time and the type of cast mold are the influencing factors of modification. The shape memory effect of the alloy is enhanced greatly by EPM.