Ultrasonic cavitation radiates huge power in a small solidifying bulk, leading to significant grain refinement, purification and homogenization of the final alloys. Ultrasound vibration has mostly been used for treating the solidification of light metals, but it is difficult to directly introduce ultrasonic vibration into copper alloy due to the lack of proper sonotrode. In this work, we have used a Sialon ceramic sonotrode to propagate acoustic waves in a Cu–Cr alloy melt. Significant grain refinement and modification of primary Cr have been obtained. With the ultrasound vibration treatment, the mechanical properties of the as-cast Cu–Cr alloy have been improved. The wear resistance of the Cu–Cr alloy has also shown enhancement with respect to the untreated alloy.

In this work, a new use of mixed Ti-6Al-4V powder, consisting of the retained powder after screening for additive manufacturing and the recycled powder after multiple printing, has been exploited. The powder mixture has been hot-isostatically-pressed (HIPed) at 930 °C/120 MPa for 3 h to reach full density. The hot deformation behavior of the as-HIPed powder compacts were investigated through isothermal compression tests, kinetic analyses, and hot processing maps. Finally, the optimized hot working parameters were validated using upsetting tests. The results show that the as-HIPed Ti-6Al-4V alloy has a fine and homogeneous microstructure. The activation energies were calculated to be 359 kJ/mol in the α + β phase regime and 463 kJ/mol in the β phase regime, respectively. The optimal hot working parameters are a deformation temperature above 950 °C and strain rate higher than 0.1 s⁻¹. The hot workability of as-HIPed powder compacts is better than the as-cast billets. The deformed microstructure can be finer than that of as-HIPed state, and the mechanical performance can be further improved by the optimal thermo-mechanical processing treatment.

Researches on erosion resistance of valves from the perspective of variable stiffness and energy mitigating are rarely to be seen so far. The ballistic protection for body armor usually requires both high strength and high energy mitigation. Based on the above characteristics of the body armor, ballistic protection for body armor is analogous to the valve plug erosion resistance. In this work, we introduce a new energy mitigating body armor inspired valve plug (EMAVP) to improve its anti-erosion performance. The EMAVP has a gradient hierarchical structure in hardness, variable stiffness materials and structures. The authors analyze the variety of stiffness and energy mitigating of the EMAVP. The fluid-structure interaction (FSI) method is used to simulate the erosion performance, the EMAVP and normal valve plug specimens were tested in the comprehensive experimental system of water hydraulic valve and jet erosion facility. Results show that the EMAVP is superior to normal valve plug, with higher energy mitigating and better anti-erosion performance.