Influence of Melting Temperature and Cooling Rate on Microstructure of a Bismuth–Manganese–Iron Alloy

Abstract

Effect of melting temperature and cooling rate on microstructure of bismuth–manganese–iron alloy was investigated using scanning electron microscopy equipped with energy-dispersive X-ray spectroscopy and quantitative analysis software. When bismuth–manganese–iron melt is cast in permanent mold or quenched in water, a large amount of BiMn phase form and dispersive Mn(Fe) particles exist in the alloy. The optimal melting temperature for bismuth–manganese–iron alloy is 1200°C for permanent mold casting. When the bismuth–manganese–iron alloy is melted at 1100°C and then quenched in water, the optimal water temperature is 45°C. When the liquid alloy is cooled in furnace, some Mn(Fe) particles and a lot of bismuth phase exist in bismuth–manganese–iron alloy with high manganese content. With the increase of the melting temperature, Mn(Fe) particles become coarser in bismuth–manganese–iron alloy with low manganese content. The elongation and tensile strength of the free-machining steel with 0.09 wt.%bismuth are lower than that of without bismuth.

Keywords:

• Bismuth–manganese–iron
• Cooling
• Melting
• Microstructure
• Solidification