Constitutive behavior of Al2O3np/Al7075 composites with a high solid fraction for thixoforming

Abstract

The thixotropic compression tests of nano-Al 2 O 3 (Al 2 O 3np) /Al7075 composites with different particle sizes and contents and containing a high fraction of solid, were conducted under conditions of 560-590 °C and 0.01-5 s-1 , and the microstructures were observed. A visco-plastic constitutive model of nanoparticle reinforced composites for thixoforming was proposed, considering the coupling effects of strain, strain rate, deformation temperature and liquid fraction and presence of nanoparticles, to describe constitutive behavior of the composites under various deformation conditions. Furthermore, the influence of deformation parameters on thixoforming was investigated. It could be shown that the predictions by the developed model were consistent with experimental results. Fracture analysis of the thixotropic compression samples revealed that high deformation temperature or/and high strain rate could prompt continuous uniform distribution of the liquid phase along the grain boundary, causing the formation of a thin liquid film around an approximately spherical grain, accordingly improving thixoformability of the

Effect of Y Addition on the Semi-Solid Microstructure Evolution and the Coarsening Kinetics of SIMA AZ80 Magnesium Alloy

“…Quantitative analysis of the micrographs of the specimens in the semi-solid state were carried out using Image-Pro Plus software (Media Cybernetics Company, Sliver Spring, MD, USA) and the statistical results of solid fraction and shape factor were determined by three OM images. The shape factor of solid particles was calculated by the following equation [22]:…”

“…The solid volume fraction varied in the range from 0.69 to 0.81 and increased with the prolonging isothermal soaking time from 5 min to 30 min. It was revealed that the semi-solid slurry with a high solid fraction between 0.75 and 0.8 had the better thixotropic behavior [6,22]. Moreover, the forming defects such as porosity, inclusions or shrinkage could be visibly prevented in the high solid fraction semi-solid feedstock during the forming process.…”

Effects of semi-solid treatment by electro-magnetic induction on micro-structure evolution and mechanical properties of the Mg-2.4Y-4Nd-0.5Zr-1Ni alloys

“…The liquid fraction was measured mainly by the liquid films between solid particles by the metallographic method. In this work, the average grain size (D eq ) of solid particles and the shape factor (°C) were calculated by the following equations: [29][30][31]…”

Effect of T6 Heat Treatment on Microstructure and Hardness of Nanosized Al2O3 Reinforced 7075 Aluminum Matrix Composites

“…Aluminum alloy matrix composites are widely used in the automobile and communication industries, as well as in military and aerospace series due to their high specific strengths, specific stiffnesses, specific moduli, and low coefficients of linear expansion properties [1]. Aluminum alloy matrix composites have recently developed into high-profile emerging materials [2,3].…”