Comparison of Age-Hardening Characteristic in Thixo-cast and Rheo-Cast T5-A356 Alloys by Nanoindenter and AFM

摘要

The nano/microstructure and mechanical/tribological properties of the eutectic regions in thixo/rheo-cast A356 alloy parts were investigated using nano/micro-indentation and mechanical scratching, combined with optical microscopy and atomic force microscopy (AFM). Most eutectic silicon crystals in the A356 alloy showed a modified morphology as fine-fibers. The aging responses of the eutectic regions in both the thixo/rheo cast A356 alloys aged at 150 ℃ for different times (0, 2, 4, 8, 10, 16, 24, 36, and 72h) were investigated. Both Vickers hardness (H_V) and indentation hardness (H_(IT)) test results showed almost the same trend of aging curves, the peak was obtained at the same aging time of 10 h, and in tribological properties of thixo/rheo-cast, the friction coefficient of thixo-cast was investigated lower than that of rheo-cast.