基体硬度和热学性质对冷喷涂TC4钛合金涂层组织和力学性能的影响

Titanium honeycomb components which suffered damage during service are usually in urgent need of timely repair. The currently prevailing repair method is melt welding, which often causes serious metallurgical defects. The relatively low operating temperature of cold spray is considered to be able to prevent the oxidation of metal particles in comparison. In our work, TC4 titanium alloy coatings were deposited by cold spray on surfaces of AA2024 aluminum alloy and TC4 titanium alloy substrates, respectively. And subsequently SEM, XRD, Vickers hardness test and three point bending test were carried out for the resultant coatings, in order to evaluate the influence of substrates' hardness and thermal characteristics on coatings' microstructures and mechanical properties. Results showed that, compared with AA2024 substrate, TC4 substrate, which owns higher hardness, lower heat capacity and lower thermal conductivity, has a less fluctuating interface with the sprayed TC4 coating, a higher particle surface temperature, and promotes the metallurgical bonding owing to the formation of a ~ 5 μm layer of adiabatic shear band among particles' contact interfaces. This contributes to the lower porosity and more satisfactory deposition effect, and in consequence, higher micro-hardness, better bending property, smooth fractured surface characterized by brittle fracture with no phase change happened. Our research confirmed the feasibility of repairing titanium alloy components by applying cold spray technique.