摘要
研究ZK31+4Si镁合金经等通道转角挤压(ECAP)后的微观组织和高温蠕变行为。结果表明,ECAP挤压可显著细化原铸态组织中粗大的汉字状Mg2Si相,并使其趋于均匀弥散分布。ECAP挤压后试样的抗蠕变性能明显优于铸态试样,在温度为473K,应力为70MPa的条件下,8道次挤压试样的稳态蠕变速率约为铸态试样的1/15,蠕变寿命提高近8倍。由稳态蠕变速率与应力的对数曲线关系求得473K下4道次挤压和8道次挤压试样的应力指数n均约为4,同时按位错蠕变机制,当应力指数n=4时,理论计算所得稳态蠕变速率与实验值非常吻合,说明在本实验条件下发生的是位错蠕变。
The microstructures and the creep behavior of ZK31＋4Si magnesium alloy processed by Equal channel angular pressing（ECAP） were investigated.The experimental results show that the coarse Chinese script-like Mg2Si precipitates are refined to fine polygonal shape particles and redistributed dispersedly after ECAP.The creep resistance is greatly enhanced after ECAP.The ctable creep rate of the 8-pass ECAPed specimen is nearly 1/15 of that of the as-cast one,and its creep life is increased by about 8 times.The curves of the minimum strain rate versus the stress show that the alloy ECAPed either through 8 passes or through 4 passes exhibit a same stress exponent n≈4.Furthermore,the theoretical calculation results according to the dislocation creep model with n=4 are well in agreement with the experimental values,indicating that the creep under the present test condition is controlled by the movement of dislocations.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2012年第5期867-871,共5页
Rare Metal Materials and Engineering
基金
山西省青年科技研究基金(2008021033)
山西省归国留学基金(2007-25)
山西省大学生创新创业专项基金(07010727)
