Microstructure and property evolution of aluminium/potassium titanate whiskers composite during Rheo-casting

Potassium titanate whiskers (PTWs) have been proved effective in improving aluminium alloys’ mechanical performance whilst reducing their thermal expansivity, which are both crucial to the industrial applications. Here, we fabricate an Al-Zn-Mg-Cu alloy composite reinforced with 10.0 vol% PTW via rheological casting and characterize its microstructure, strength and thermal expansivity evolution at different process parameters. The distribution of PTW in alloy matrix was more homogeneous with growing treating time. After 40 s semi-solid slurring, the final average length of PTW was reduced to 4.1 μm. Meanwhile, the ultimate tensile strength of the composite gained ca. 27.0 % increase, and the thermal expansivity was significantly reduced. Our results demonstrate the feasibility to fabricate high-performance aluminium/PTW composite while reducing the PTW addition via semi-solid rheological processing. Our findings also help better understand the crushing and dispersing behavior of PTW in aluminium matrix during semi-solid solidification.