A comparative study on hot dynamic compaction and quasi-static hot pressing of Al7075/SiCnp nanocomposite

摘要

Quasi-static and hot dynamic compactions of Al7075/SiC nanocomposite powder are studied in this work. Mechanically milled micron-sized Al7075 with different amounts of SiC nano particles (SiCnp), 0 vol%, 5 vol%, and 10 vol%, are used to fabricate the samples. Dynamic and quasi-static hot compaction is conducted at strain rates of 10(3) s(-1) and 8 x 10(-3) s(-1), respectively. The hot compaction conducted at the process temperature of 698 K produces nanocomposite samples with relative densities up to 98%. The microstructural and mechanical behaviors of samples such as micro hardness and stress-strain curves under quasi-static and dynamic loadings are also investigated. The results show improvement in micro hardness of the material. The quasi-static and dynamic tests are carried out using Instron testing machine and split Hopkinson pressure bar (SHPB), respectively. The improvement is believed to be due to strengthening mechanisms such as Orowan and enhanced dislocation density induced by thermal mismatch phenomenon and not by grain refinement described by the Hall-Petch effect. The results from quasi-static compressive tests reveal higher strength for quasi-static hot pressed samples than those produced under dynamic compaction. However, the dynamic compressive tests using SHPB indicate similar compressive strength for both quasi-statically and dynamically compacted samples. (C) 2014 The Society of Powder Technology Japan. Published by Elsevier B. V. and The Society of Powder Technology Japan. All rights reserved.