Tool traverse speed-mediated microstructure and texture engineering for enhanced strength-ductility-corrosion resistance synergy in ZK60 magnesium alloy
Journal
Materials Chemistry and Physics
Journal Volume
361
Start Page
132672
ISSN
02540584
Date Issued
2026-08-01
Author(s)
Abstract
A strain-rate-controlled microstructural design strategy is proposed to enhance strength-ductility-corrosion resistance synergy in extruded ZK60 magnesium alloy via friction stir processing (FSP). By systematically varying the tool traverse speed (TTS:100−200mm/min), the interplay between strain rate and heat input was tailored to regulate dynamic recrystallization (DRX), crystallographic texture, and precipitate stability. FSP induced significant lattice rotation, resulting in orientation transition from prismatic/pyramidal to basal-dominated, which facilitated extensive grain fragmentation, leading to grain refinement from ∼15μm in the extruded state to <8μm after processing. Increasing TTS increased the strain rate while reducing heat input, resulting in fine DRX grains, weak basal texture, and enhanced Σ13a coincident site lattice (CSL) boundaries. Concurrently, MgZn2 precipitates underwent fragmentation and partial dissolution. Deformation transitioned from slip-dominated parabolic flow in the extruded condition to sigmoidal flow in FSPed samples, governed by {101‾2}⟨101‾1⟩ extension twins (ET) activation. The yield strength decreased at 100mm/min due to early ET activation under relatively coarser grains and stronger basal texture, but recovered at higher TTS through grain refinement. Ultimate tensile strength increased post-FSP due to ET-induced geometric hardening. Notably, the sample processed at 200mm/min achieved an excellent strength-ductility synergy, due to combination of refined grains and weakened texture. The refined microstructure, increased Σ13a CSL boundaries, and precipitate dissolution collectively suppressed micro-galvanic coupling and promoted uniform surface degradation. As a result, the corrosion current density decreased by more than an order of magnitude compared to the extruded condition, with the lowest observed at 200mm/min.
Subjects
Corrosion
Mechanical property
Microstructure
Texture
Tool traverse speed (TTS)
Publisher
Elsevier Ltd
Type
journal article