Influence of micro-addition of lanthanum on grain characteristics, mechanical properties, and corrosion behavior of CuAlNiMnLa shape memory alloy

The study investigated the grain size criteria, mechanical characteristics, and corrosion behavior of Cu-14Al-4.5Ni-0.7Mn shape memory alloy (SMA) with the micro-addition of 0.06 wt% Lanthanum (La). Using standard melting and casting procedures, the alloy compositions were melted at 1300 ℃ in an arc furnace with an argon atmosphere. The cast compositions without thermal treatment were machined and tested for physical properties including density and percentage porosity, corrosion behavior, and mechanical properties like hardness, ultimate tensile strength, yield strength, fracture strain, percentage elongation, specific strength, and fracture toughness. The average grain size, profile plot, and grain size distribution were all determined using ImageJ software. The microstructural observations revealed the presence of α-phase, β-phase, and intermetallic phases, including the coarse α+γ2 phase, which contributed to the improved characteristics. The inclusion of lanthanum resulted in a drop in the average grain size of the parent alloy from 9.25 μm to 6.08 μm, indicating a clear correlation between property improvement and microstructure refinement. The composition's tensile strength