DETERMINATION ON THE EFFECT OF TIN CONTENT ON MICROSTRUCTURE, HARDNESS, OPTIMUM AGING TEMPERATURE AND AGING TIME FOR SPINODAL BRONZE ALLOYS CAST IN METAL MOLD

摘要

A study was conducted to determine the effect of tin content on microstructure, hardness, optimum aging temperature and aging time of spinodal bronze alloys cast in metal mold. Copper, nickel and tin with appropriate compositions were melted in an electric furnace under argon atmosphere and were cast into metal molds. The cast specimens were solutionized at 825 degrees C for 10 h and were aged at 250, 300, 350, 400 and 450 degrees C for 1-5 h. The solutionized and aged specimens were subjected for microstructural evaluation and hardness testing. It was observed that the grain boundary precipitates form upon over-aging. The peak hardness increases with increase in tin content from 4 to 12 wt% in solutionized and aged condition. The peak aging time was found to remain a constant with increase in Sn content. The optimum aging temperature and aging time were also determined for spinodal bronze alloys cast in metal mold.