The effects of rolling deformation on microstructure and mechanical properties of cold spraying Ti

Due to porosity and lack of metallurgical bonding, cold-sprayed Ti (CS-Ti) shows insufficient mechanical properties, especially plasticity. Here we investigate the effect of rolling deformation on the microstructure and mechanical properties of CS-Ti. The results show that a 20% deformation reduces the porosity of the CS-Ti from 2.76% to 0.58%, achieving complete metallurgical bonding and recrystallization. Consequently, the ultimate tensile strength (UTS) increases from 346 MPa to 658 MPa, and the elongation (EL) improves from 0.25% to 6.10%. When the rolling deformation increased to 60%, the porosity further decreases to 0.04%, with the microstructure consisting mainly of elongated α-Ti grains and high-density dislocations. The corresponding UTS and EL are 800 MPa and 3.89%, respectively. Analysis of the tensile fracture indicates that, with the deformation increased, the failure mode changes from ductile fracture to ductile-brittle fracture. The results show that the combined effect of thermal effect and mechanical deformation can effectively promote the pore closure and interface reconstruction, and significantly improve the mechanical properties of the CS-Ti.