半固态铝硅合金的压缩变形行为与组织变化

Compressive deformation behavior and microstructure of semi-solid Al-Si alloy

研究了控制熔体结晶法制备的半固态ZL101合金的压缩变形行为以及显微组织的变化。结果表明:在液固相区二次加热并保温足够时间后,该合金的球状固相仍保持半固态加工要求的适当尺寸,575℃和582℃压缩变形时,半固态浆料具有稳定触变流动变形特征,即应力随应变增大而缓慢下降,其应力水平较接近固相线的高温(550℃)塑性变形应力低得多;枝晶组织和高变形速率提高半固态合金的变形应力,并使应力随应变增大而单调提高;大变形后,圆柱试样中心和边缘区域存在球状初生α相变形程度的不同。半固态变形中,变形机理从以阻尼液相流动为主变为以固相颗粒塑性变形为主。

Compression experiments were carried out to investigate deformation behavior and microstructure of semi-solid ZL101 alloy fabricated by controlled crystallization technique. The results show that the alloy has reasonable size of globular solid required for semi-solid processing after reheating to temperatures in liquid-solid range and sufficient holding time. The semi-solid slurry has stable thixotropic flow deformation behavior under compressing at 575℃ and 582℃, i.e. stress decreasing gradually with strain increasing, and in this case, the deformation stress is much lower than that of the specimen deformed at temperature (550℃) close to solidus. Both dendritic structure and high strain rate enhance the deformation stress of the semi-solid alloy, and enable the stress to increase with strain continuously. The deformation degree difference of globular primary α phase appears at center and edge areas in the cylinder specimen after large deformation. The deformation mechanism of damped liquid flow domination becomes solid particle plastic deformation domination during deformation in semi-solid state.