Influence of the sintering method on microstructure and microhardness of AlCuNiSnZn-based high-entropy brasses and bronzes obtained by powder metallurgy

The present report focused on synthesizing and characterizing a series of AlCuNiSnZn alloys obtained by powder metallurgy as a new family of high-entropy brasses and bronzes. The (AlCuNi)₈₀Sn₁₀Zn₁₀ and (AlCuNi)₇₀Sn₁₅Zn₁₅ alloys were obtained by mechanical alloying and sintering, evaluating two sintered methods: high-frequency induction heat and conventional. After 10 h of mechanical alloying, the elemental powder mixture formed solid solutions of face-centered cubic (FCC-α) and body-centered cubic (BCC-β) phases. However, the solid solutions, after sintering, were decomposed into a mixture of γ Ni₂Zn₁₁, AlNi, and Cu₂Ni₃Sn₃ phases. The (AlCuNi)₈₀Sn₁₀Zn₁₀ system sintered by high-frequency induction heat exhibits a microhardness value of ∼501 HV±17, while that obtained by the conventional method was ∼320 ± 21 HV. The results showed that it is convenient to maintain the BCC/FCC solid solutions after sintering due to their stability and properties. In addition, it is necessary to design alloys with lower values of ΔH_mix to improve the microhardness.