Interparticle Bonding Process of Metal Powder by Cyclic Unidirectional Sliding

Abstract

In this study, a repetitive unidirectional friction experiment was conducted on uniaxially compressed sample of metal powder in order to clarify the behavior of solid-state bonding on metal powder particles by simultaneous application of compressive and shearing force. Pure Cu powder was compressed under the normal stress of 1000 MPa to get uniaxially compressed sample with the target size of 20×20×0.25 mm³. The relationship between a normal load, a number of sliding cycles, and microstructural changes of samples after the unidirectional friction experiment was investigated by observing sample structures of fracture surfaces and cross-sections. As the results, it was found that the applied stress is more dominant in the particle bonding than the strain. In addition, it was suggested that the bonding of powder particles is proceeded as this order: (1) plastic deformation of particles; (2) grain refinement to a size of several micro-meter; (3) bonding of particles; (4) additional grain refinement to submicron size.