剧烈塑性变形引起的LZ91镁合金微管的强度-塑性协同强化  

Strength-plasticity Synergistic Strengthening of LZ91 Magnesium Alloy Microtubules Induced by Severe Plastic Deformation

作　　者：周逸文 许虎 蔡维 严凯[1] ZHOU Yiwen;XU Hu;CAI Wei;YAN Kai(College of Mechanical Engineering,Yangzhou University,Yangzhou 225127,China)

机构地区：[1]扬州大学机械工程学院,江苏扬州225127

出　　处：《热加工工艺》2024年第19期107-111,共5页Hot Working Technology

摘　　要：采用原材料挤压棒+终挤压和等通道挤压(ECAP)棒+终挤压分别制备了外径2 mm和壁厚0.3 mm的LZ91镁合金微管。研究了两种方式得到的微管组织和力学性能。结果表明,加入ECAP后,微管的屈服强度、抗拉强度和伸长率分别由170、185 MPa和22%提高到200、210 MPa和30%。这主要是由于ECAP造成了显微组织的细化的同时使原始组织中就存在的Mg O和ZnO转换为弥散分布的纳米尺寸颗粒。这些纳米氧化物在后续的挤压过程中促使基体发生动态再结晶并提高显微组织的热稳定性,室温拉伸中会造成位错运动阻力和加工硬化率的上升,从而同时提高了微管的强度和塑性。LZ91 magnesium alloy microtubules with an outer diameter of 2 mm and a wall thickness of 0.3 mm were prepared by raw material extrusion rod+final extrusion and equal-channel angular pressing(ECAP)rod+final extrusion,respectively.The microtubule microstructure and mechanical properties obtained in two ways were investigated.The results show that after adding ECAP,the yield strength,tensile strength and elongation of microtubules increase from 170,185 MPa and 22%to 200,210 MPa and 30%,respectively.This is mainly due to the fact that the microstructure is refined by ECAP and the MgO and ZnO existing in the original structure are converted into dispersed nano-sized particles.These nano-oxides promote the dynamic recrystallization of the matrix and improve the thermal stability of the microstructure during the subsequent extrusion process.Room-temperature tension can cause the dislocation motion resistance and the processing hardening rate increases,which simultaneously increases the strength and plasticity of the microtubules.

关 键 词：LZ91镁合金 镁合金微管 等通道挤压(ECAP) 氧化物弥散强化 强度塑性协同强化 

分 类 号：TG379[金属学及工艺—金属压力加工]