纯镁切应力变形后的微观组织演变、力学性能、腐蚀行为

Microstructure Evolution, Mechanical Properties and Corro-sion Behavior of Pure Magnesium Deformed by Shear Stress

摘要:

纯镁为密排六方结构，具有较少的独立滑移系导致其塑性较差。研究了纯镁变形后的微观组织演变、力学性能、腐蚀行为。结果表明，纯镁经过等径角挤压（ECAP）变形后晶粒明显细化以及基面织构发生了弱化，导致纯镁的塑性得到了显著地提高。等径角挤压变形后纯镁强度降低主要是因为基面织构弱化影响大于晶粒细化。此外，等径角挤压变形后纯镁自腐蚀电位和腐蚀电流密度明显增加，纯镁的抗腐蚀性能显著提高。纯镁的腐蚀机理可能从局部腐蚀向均匀腐蚀转变，从而减少了样品在标准模拟体液浸泡中的腐蚀脱落，确保了试样的完整性。

Abstract:

The close-packed hexagonal structure pure magnesium has few independent slip systems which result in poor plasticity. In the present paper, the pure magnesium was deformed by equal channel angular pressing (ECAP). Results show that due to grain refinement and weakening of base texture, plasticity of pure magnesium is significantly improved. The strength of pure magnesium decreases after ECAP deformation mainly because the influence of base texture weakening is greater than that of grain refinement. Moreover, the corrosion resistance of pure magnesium is significantly enhanced after shear stress deformation because of the increase of self-corrosion potential and corrosion current density. The corrosion mechanism of pure magnesium may change from local corrosion to uniform corrosion, which can reduce the corrosion falling and ensure the integrity of samples during immersion in the standard simulated body fluid.