AZ31镁合金高温蠕变机理的研究.PDFVIP

高温低应力下AZ31 镁合金的蠕变性能及蠕变机理* 张诗昌 宗 钦 胡衍生 程晓茹 （武汉科技大学钢铁冶金与资源利用教育部重点实验室 武汉 430081） 摘要：研究了AZ31 镁合金在高温、低应力下的蠕变性能及蠕变机理。结果表明：AZ31 镁合金的高温蠕变具有明显的三阶段 蠕变特征；随着温度和应力的增加，稳态蠕变速率增加，稳态蠕变速率区域缩短。温度大于 420 ℃、较低应力时，AZ31 镁 合金的蠕变为晶界扩散控制的COBLA蠕变；较高应力时，与位错攀移控制的WEETMAN蠕变机制相吻合。当温度为 320~420 ℃ 时，AZ31镁合金的蠕变为滑移控制的位错蠕变。计算了由COBLA蠕变向WEETMAN蠕变转变的临界应力σ ，该应力与P-N力τ 在 cr p 数值上具有如下关系：σ ≈(2-3)τ 。 cr p 关键词： AZ31镁合金 高温蠕变 蠕变机理 中图分类号：TG113.2 Creep Property and Mechanism of AZ31 Magnesium Alloy under High Temperature and Low Stress ZHANG Shichang ZHONG Qin HU Yansheng CHEN Xiaoru （Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 ） Abstract : The creep property and mechanism of AZ31 magnesium alloy under high temperature and low stress is investigated. The results show that the creep curve presents obviously the three stages creep characteristic. The creep rate increases and the static creep stage shortens with increasing temperature and stress. When temperature is above 420 ℃,the creep of AZ31 magnesium alloy under lower stress is COBLA creep controlled by grain boundary diffusion of magnesium; however, at higher stress the creep accords with WEETMAN creep controlled by dislocation climb. The creep of AZ31 magnesium alloy is controlled by dislocation glide at temperature ranging from 320 ℃ to 420 ℃. The critical stress σ which results in changing from Cobla creep to Weetman creep is cr calculated, the magnitude of σ and the Nabarro-Peieris stress τ has the relation as follow: σ ≈(2-3)τ .