Search

The distribution of second-phase particles is crucial to the mechanical properties of particulate reinforced copper matrix composites (PRCMCs). Ultrasonic vibration treatment (UVT), as an effective technique to disperse second-phase particles in metallic melts, has been extended to treat PRCMCs using a SiAlON sonotrode. In this study, systematic experiments have been conducted to explore the effect of UVT on the microstructures and mechanical properties of in situ Cu-TiB 2 composites. The results indicated an optimal duration of UVT for 3 min, featured by an improved distribution of TiB 2 particles and superior mechanical properties of the as-cast composite. The ultimate tensile strength, yield strength, and elongation exhibited significant increases of 15.7%, 18.1%, and 36.1%, respectively, compared to the as-cast Cu-TiB 2 composite without UVT. Furthermore, these experimental composites were subject to rolling deformation. The results once again demonstrated that the as-rolled Cu-TiB 2 composite, treated with UVT for 3 min, stood out as the best. The ultimate tensile strength, yield strength, and elongation of the as-rolled Cu-TiB 2 composite were 459 MPa, 422 MPa, and 7.0%, respectively. Based on the microstructural observation, the mechanism underlying the UVT-induced enhancement of mechanical properties was discussed in terms of the non-linear effects of ultrasound cavitation on liquid metals. This work can provide a strategy for producing high-performance PRCMCs through UVT. • Cu-1 wt% TiB 2 composites are successfully prepared by combining UVT and in-situ synthesis. • UVT can eliminate TiB 2 particles from agglomerating and obtain homogeneous microstructure. • Ultrasonic-assisted in situ casting improves both the strength and ductility of Cu-TiB 2 composites. • The effect of UVT is positively related to time only in some time ranges. [ABSTRACT FROM AUTHOR]

This work aims to investigate the electrical sliding wear behavior of the dual-scale particulate reinforced copper matrix composites by a self-developed pin-on-disk wear tester. Cu- x Cr-0.3Zr-1ZrB 2 (x = 0, 0.5, 1.0) composites were fabricating by casting and cold rolling. The microstructure of worn surfaces was examined using scanning electron microscopy (SEM) and laser scanning confocal microscope to unravel the wear mechanisms. The results indicated that the combined effect of mechanical wear and electrical wear dominated the wear process with an increase in the apparent normal load. Amplifying the electrical current increased the wear loss of the sliding pair, in the meantime alleviated the fluctuation of the friction coefficient with marginal changes in the average values. After introducing Cr element and ZrB 2 particles, the wear rate decreased from 0.197 mg/m to 0.141 mg/m under moderate operating test conditions. Adhesive wear and abrasive wear occupied an important position in the wear mechanism of the Cu-1wt%Cr-0.3wt%Zr-1wt%ZrB 2 composite under electrical current due to the elevation of thermal stability and the formation of a tribolayer introduced by these reinforcements. [Display omitted] • The Cu-1Cr-0.3Zr-1ZrB 2 composite stands out with the best tribological properties. • High apparent contact load changes the wear mechanism from abrasive to arc erosion. • Amplifying the electrical current results into the increased Joule and arc heat effects. [ABSTRACT FROM AUTHOR]