Stress-enhanced grain growth in a nanostructured aluminium alloy during spark plasma sintering

Abstract

In this study, we report on the influence of high pressure on the microstructure evolution of cryomilled nanostructured Al alloy powders during spark plasma sintering (SPS). Our experimental results suggest that the particular mechanism that governs grain growth during SPS depends on the magnitude of the applied pressure. In the case of material consolidated at a high pressure (e.g. 500 MPa), grain coarsening occurs via a combination of thermally activated grain boundary (GB) migration, stress-coupled GB migration and grain rotation-induced grain coalescence. In contrast, in the case of the material consolidated at a low pressure (50 MPa), grain growth occurs primarily via thermally activated GB migration.

Keywords:

• aluminium alloy
• nanostructured materials
• spark plasma sintering
• grain growth mechanism
• high pressure

Additional information

Funding

Funding. This work was supported by the US Army TACOM-ARDEC [grant number W05QKN-09-C-118] and [grant number W15QKN-14-C-0056]; Young Scientist Foundation of Shandong Province, China [grant number BS2009CL043]; Innovation Foundation of Shandong University, China [grant number 2012TS032].