Ultra-high pulse pressure induced particle surface thermal field assisted preparation of W–Al composite

Abstract

Particle surface thermal field (PSTF) is an inhomogeneous thermal field that concentrates the heat effect on the surface of particles, and it can be utilized to fabricate composite materials with large differences in physical properties. However, it is difficult to form PSTF with large temperature gradients to meet the preparation requirement of materials with extreme differences in physical properties. In our work, a PSTF is proposed and realized by an ultra-high pulse pressure (UHPP) to prepare W–Al composite, the PSTF has a heating effect on the powder interface with a low-temperature interior of the powders. The combination of ex-situ microstructural observation and in-situ molecular dynamic simulation microstructural snapshot is used to demonstrate the densification mechanism. The PSTF is characterized as the temperature higher than 1200 °C on the W–Al powders interface but lower than 200 °C interior of the powders. The densification mechanisms are explained as interfacial jet penetration, interfacial friction welding and interfacial melting. In addition, interfacial temperature distribution creating gradient pressure on the W–Al interface illustrated the generation of gradient Al grains on the W surface, thus creating a high mechanical micro-hardness of 249.8 Hv and compressive strength of 473.2 MPa for the W–Al composite.