Preparation of Al_2O_3/TiO_2 particle-reinforced copper through plasma spraying and friction stir processing

摘要

In this study, Al_2O_3/TiO_2 particle-reinforced copper matrix surface composites were successfully processed via friction stir processing (FSP). A "sandwich" lap joint setup subjected to multi-pass FSP was adopted. The composite layer with a thickness of -2200 μm was achieved after triple-pass processing. The Al_2O_3 and TiO_2 particles were evenly distributed in copper matrix and the grains were refined due to the stir and crush action of tool. The defects such as pores and interlamellar contacts in the as-sprayed layer disappeared with the particles involved into substrate. Vickers hardness test were implemented and the average hardness value achieved 448 HV_(0.1) after triple-pass processing, which was about 4 times higher than that of the T2 copper. Shearing tensile tests were carried out and the maximum shearing force reached to 7.98 kN. Real-time temperature change showed that the traveling speed has little effect on the T_m variation of stirring zone. Furthermore, the softening temperature of FSPed samples was higher than 900 ℃ which represents a better thermal stability.