Grain characteristics and mechanical properties of as-cast Cu-10%Al alloy: Effects of alloying additions

Abstract

In this research, a study between the microstructure and mechanical properties of Cu–10%Al alloy with the single addition of V, Ni, Mn, Nb and Cr at 5 wt% was carried out. This work aims to analyse the grain size criterion of Cu-10% Al alloy with various alloying elements. Six synthetic alloys of Cu%10Al were produced by sand casting using a bailout crucible furnace. Mechanical properties such as ultimate tensile strength, percentage elongation, hardness, and impact strength were determined on the alloys. The structural properties were examined by an optical metallurgical microscope and scanning electron microscopy (SEM). The average grain size, profile plot and grain size distribution were also determined using ImageJ software. The results indicated that Cu10%Al alloys with alloying elements had improved mechanical properties compared to Cu–10%Al alloy without alloying elements. Cu–10%Al–5%Nb alloy showed the optimum performance in terms of ultimate tensile strength and percentage elongation, while Cu–10%Al–5%Mn alloy gave peak value of hardness and impact strength. From structural observation, α-phase, β-phase, and intermetallic phases such as fine stable reinforcing kappa phase and coarse α+γ2 phase were detected and allied to the properties enhancement. The properties improvement is directly dependent on the grain refinement of the microstructures as the average grain size of the parent alloy decreased from ≈16.54 μm to ≈11.08 μm after the adding of alloying elements.