Effect of Strain Rate on the Microstructure Evolution and Compressive Deformation Behavior of High-Strength Cu Bulk Material Manufactured by Cold Spray Process

Abstract

This study investigated the effect of strain rate (10−3-10/s) on the compressive properties of pure Cu bulk material at room temperature manufactured by cold spray process. Initial microstructural observation confirmed the sizes of ultra-fine grains to be in hundreds of nm, with dynamic recrystallization on deposited particle interfaces, and the average grain size was found to be 3.14 μm. The compression test at room temperature showed yield strength of 314-368 MPa at initial strain rate of 10−3-10/s, at a level similar to that of materials produced with the severe plastic deformation process. Meanwhile, during compressive deformation at all strain rates, work hardening occurred first, and a unique deformation behavior of work softening occurred thereafter after a certain strain. Moreover, as strain rates increased, the rates of work hardening and work softening increased simultaneously. The microstructural observation after the compressive deformation confirmed microstructure evolution in all materials, and as the strain rate increased, the average grain size decreased, and a more uniform structure was formed. Based on the above findings, this study discusses the deformation behavior in correlation with the microstructures of the cold-sprayed Cu materials at different strain rates.