Elucidating the nanoscale atomic transport during shear-induced mixing in additive friction stir deposition of Al-Mo alloy

About the Event

This study investigated the progression and mechanisms of alloying in Al-Mo binary alloys during additive friction stir deposition (AFSD). The intense shearing in the immiscible Al–Mo system during AFSD establishes a self-organized steady state, featuring finite-scale compositional domains enriched in either Al or Mo. This pattern results from the dynamic interplay between kinetic roughening at interfaces and thermal diffusion, fostering compositional self-organization. Hot working nature of AFSD promotes the formation of fine Al-Mo intermetallic particles, ~200 nm in average size. These particles are predominantly Al12Mo with a small fraction of Al5Mo. The alloying reaction is primarily controlled by interdiffusion through the Al₁₂Mo phase. A crucial mechanism for nanoscale particle formation is the efficient removal of the Al₁₂Mo phase from the Al–Mo interface, driven by strong shear forces from the rotating tool. This research demonstrates a promising method for synthesizing bulk Al–Mo intermetallic particle-strengthened aluminium alloys through solid-state processing.

About the Speaker

Abhishek Rastogi, Ph.D. is a Postdoctoral Associate in Materials Science and Engineering at Virginia Tech, where his research focuses on solid-state additive manufacturing using additive friction stir deposition (AFSD) for aluminium alloys. His work emphasizes process– microstructure–property relationships, solid-state recycling of scrap alloys, and shear-driven atomic mixing mechanisms, supported by advanced electron microscopy including SEM, EBSD, FIB, and TEM. He has led multiple industry-relevant R&D projects involving alloy qualification, defect mitigation, and post-process heat-treatment optimization. Abhishek received his Ph.D. from IIT Delhi, specializing in deformation-induced phase transformations in metastable β-titanium alloys.