Microwave flash sintering of metal powders: From experimental evidence to multiphysics simulation

TL;DR

This paper introduces a microwave flash sintering method for metals, demonstrating rapid densification of Ti-6Al-4V powder through experimental and multiphysics simulation, revealing resonance effects as key to the process.

Contribution

It presents the first microwave flash sintering technique for metals and develops a multiphysics model explaining the resonance-driven thermal runaway.

Findings

Rapid (60 s) sintering of Ti-6Al-4V achieved experimentally.

Simulation accurately predicts microwave distribution and densification.

Microwave sintering significantly accelerates metal powder sintering kinetics.

Abstract

Flash sintering phenomena are predominantly associated with ceramics due to thermal runaway of their electric conductivity noticeably represented in materials such as zirconia or silicon carbide. Because of their high electric conductivity, flash sintering of metals is nearly inexistent. In this work, an original metal powder flash sintering method based on a microwave approach is presented. Within the developed approach, an unusually fast (60 s) thermal and sintering runaway of Ti-6Al-4V powder is experimentally revealed under microwave illumination. This phenomenon is simulated based on an electromagnetic-thermal-mechanical (EMTM) model. The developed multiphysics model reveals that the metal powder specimen's runaway does not result from its intrinsic material properties, but results from the resonance phenomenon thermally activated by the surrounding tooling material. The EMTM simulation predicts with a very good accuracy the microwave repartition and the resulting densification and powder specimen's shape distortions observed experimentally. The comparison of the microwave and conventional sintering kinetics indicates an important acceleration of the sintering behavior under microwave heating. The developed sintering approach has a potential of the implementation for time-effective mass production of small metal parts.