Characterization of Cu-13Al-3.5Ni-0.7Ti-(0, 0.5, 1) Y Alloy Prepared by Mechanical Alloying, Sintering, and Hot Rolling

The Cu-13wt.% Al-3.5wt.% Ni-0.7wt.% Ti- (0, 0.5, 1) wt.% Y alloy was produced from a powder mixture by mechanical alloying, sintering and hot rolling. The mechanically alloyed powders were compressed, sintered, hot rolled, and heat treated to prepare a bulk alloy with a martensitic phase. Also, the effects of yttrium addition (0.5 and 1 wt.%) were studied on the properties of produced powder and bulk alloy. X-ray diffraction (XRD) analysis proved the formation of (Cu-Al-Ni) α phase after 20 h milling and martensite formation after hot rolling and heat treatment of the alloy. Optical and scanning electron microscope (SEM) images showed little amounts of porosity after hot rolling and heat treatment. It is found that adding yttrium caused a better distribution of alloying elements in the matrix by creating a secondary intermetallic phase (probably Al₃Y) and a finer grain size. Hardness measurements indicated an increment in hardness from 158 HV for Y-free alloy to 187 HV in 1wt.% Y-containing alloy. The transformation temperatures of these samples were determined by differential scanning calorimetry (DSC). Yttrium addition affected the shape memory properties by increasing the martensite-to-austenite transformation temperature from 41.5 °C for Y-free alloy to 58.5 °C in 1wt.% Y-containing alloy after hot rolling and heat treatment.