Effect of Semi-solid Solution and Aging on Microstructure and Properties of Mn-Cu Alloy

Mn65-Cu23.75-Zn3-Al3-Ni3-Fe2-Ce0.05 (at%) alloy was prepared by vacuum induction melting method, and then rolled at 400 degrees C with a height reduction of 40% and further annealed at 800 degrees C for 5 h. The alloy samples were solid solution and semi-solid solution treated at 850 degrees C and 950 similar to 1050 degrees C for 20 min, respectively, and then aged at 430 degrees C for 0 similar to 16 h. The effects of semi-solid solution temperature and aging time on the microstructure, damping capacity and mechanical properties of Mn-Cu alloys were studied. The results show that the microstructure of solid solution treated alloy is composed of a single gamma-MnCu phase, while that of the semi-solid solution treated one comprises Mn-rich and Mn-poor gamma-MnCu phases. The amount of Mn-poor gamma-MnCu phase gradually rises with the increase in semi-solid solution temperature. The damping capacity of the alloy firstly increases and then deceases with the increase of aging time. Under optimal aging conditions, the damping capacity of the alloy is improved at a relatively lower semi-solid solution temperature while degraded at a relatively higher semi-solid solution temperature. The tensile properties of the alloys semi-solid solution treated at 950 and 1000 C are improved compared to the alloy solid solution treated at 850 degrees C (especially, the product of strength and ductility of 5950 alloy is 70% higher than that of S850 one). However, the product of strength and ductility of the alloy decreases instead with further increase in semi-solid solution temperature.