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In this study, NiAl bronze (NAB) alloys are processed using an ultrasonic vibration-assisted milling (UVAM) surface engineering technique. The strengthening mechanisms at different cutting speeds are analysed through well-established models and experiments. The increase in cutting speed produced decrements of 29.5%, 26.6%, and 5.6% in the friction torques, accumulated dissipated energy, and worn surface area, respectively. The microhardness gradually increased by 11%, which helped improve the fretting wear performance. Grain refinement, precipitation, and dislocation strengthening were the main mechanisms. Grain refinement (∆ σ HP) had the greatest contribution to performance, followed by precipitation (∆ σ or) and dislocation (∆ σ d). Nanotwin strengthening was observed at a cutting speed of 150 m/min. Martensite nanotwins may nucleate at the grain boundary and grow toward the grain interior. [Display omitted] • The increase of cutting speed leads to beneficial effects on their fretting behavior including friction torques, accumulated dissipated energy and worn surface area for 29.5%, 26.6% and 5.6%, respectively. • The refinement of the κ phases and the effects of dislocations and stacking faults help increase the hardness and mechanisms were analysed. • The formation of martensite phases in UVAM6000 was attributed to severe plastic deformation and the special 3R martensitic structures of NAB alloys. Specifically, martensite nanotwins may nucleate at the grain boundary and then grew toward the interior of grains. • Grain refinement, precipitate, and dislocation strengthening were the main mechanisms for all samples and its contributions were calculated through well-established models and experiment data. [ABSTRACT FROM AUTHOR]

In current work, the wear resistance of CuNiAl was improved by the application of an aromatic thermosetting co-polyester (ATSP)-based coating on its surface. Tribological behaviors of the ATSP coating at stresses of 1.52, 3.04 and 3.75 MPa under different lubrication conditions (dry friction and oil) were studied by the fretting wear test. The morphology and chemical composition of the coating were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy and three-dimensional (3D) optical microscope. Results showed that at the same conditions, the friction torque of the ATSP coating was lower than that of CuNiAl. Significantly, wear was reduced by more than 90% after the application of the ATSP coating. The wear mechanism of the ATSP coating was slight deformation with pits induced by plastic deformation and fatigue crack propagation. The ATSP coating underwent molecular chain breakage during wear and chemical reaction with the friction pair to form a transfer film which played an important role in the reduction of wear. • The friction and wear properties of ATSP coating under fretting wear were investigated. • ATSP coating can significantly improve the wear resistance of CuNiAl. • ATSP coatings undergo complex chemical changes during wear。. • Transfer film is an important factor in reducing ATSP friction and wear. [ABSTRACT FROM AUTHOR]