Dislocation Transformations at the Common 30°〈0001〉 Grain Boundaries During Plastic Deformation in Magnesium

Area of Science:

• Materials Science
• Metallurgy
• Solid Mechanics

Background:

• Thermal-mechanical processing of magnesium (Mg) alloys creates numerous 30°⟨0001⟩ grain boundaries (GBs).
• These GBs significantly influence the mechanical properties of Mg alloys through interactions with lattice dislocations.

Purpose of the Study:

• To systematically investigate the influence of 30°⟨0001⟩ GBs on slip transmission during plastic deformation in Mg alloys.
• To elucidate the mechanisms of dislocation interaction with GBs in hexagonal close-packed (HCP) metals.

Main Methods:

• Systematic investigation of dislocation behavior at 30°⟨0001⟩ grain boundaries.
• Analysis of slip transmission, transmutation, and absorption of dislocations across GBs.

Main Results:

• Basal dislocations can transmute and continue gliding on the basal plane in the neighboring grain.
• Prismatic dislocations can transmit across GBs while maintaining their Burgers vector.
• Mobile pyramidal c+a dislocations are absorbed at GBs, leading to new grain formation.

Conclusions:

• The study provides a comprehensive understanding of grain boundary-dislocation interactions in Mg alloys.
• Findings highlight the critical role of GBs in controlling plastic deformation mechanisms in hexagonal close-packed metals.