Correlation between the thermal responses and microstructure patterns in aluminum-based Silicon carbide composites (SiC_p/Al) Consolidated by different high pressure torsion schemes

摘要

High pressure torsion of powder mixture is a novel strategy for manufacturing high-quality aluminum-based silicon carbide composite SiCp/Al billet used in electronic packaging, however, the correlation between thermal properties and the high pressure torsion process and the related mechanisms are still unclear. To this end, the variation rules of thermal expansion coefficient and thermal conductivity with high pressure torsion turns are studied and the corresponding microstructure morphology and dislocation patterns are observed by optical and transmission electron microscopes. The results show that thermal expansion coefficient decreases monotonically but thermal conductivity first increases then decreases with the increase of high pressure torsion turns. Moreover, the results of differential scanning calorimetry experiments indicate the decrease of recrystallization temperature with turns of high pressure torsion. The non-monotonic variation of thermal conductivity is attributed to the combined effect of the improved relative mass density brought by the consolidation effect and the dislocation tanglement and pattern transformation (formation of in-situ sub-grains) during high pressure torsion process.