往复挤压Mg-4Al-2Si合金时Mg_2Si颗粒的破碎规律  

Breaking Law of Mg_2Si Particles in Mg-4Al-2Si Alloy during Reciprocating Extrusion Process

作　　者：宋佩维[1] 

机构地区：[1]陕西理工学院,汉中723003

出　　处：《机械工程材料》2011年第7期75-80,共6页Materials For Mechanical Engineering

基　　金：陕西省自然科学基础研究计划资助项目(2010JM6009);陕西省教育厅自然科学专项科研计划资助项目(2010JK470)

摘　　要：采用往复挤压工艺细化Mg-4Al-2Si(AS42)镁合金组织,研究了挤压过程中Mg_2Si颗粒的细化效果、破碎特征、分布规律及破碎机制。结果表明:从铸态到挤压8道次态,随挤压道次的增加,颗粒不断细化,均匀度和弥散度逐渐提高;挤压11道次时,颗粒发生粗化;合金在400℃、应变速率0.01s^(-1)条件下的压缩峰值应力约为75MPa,大于Mg_2Si颗粒的断裂应力(48MPa),挤压使颗粒发生开裂;随挤压道次的增加,位错密度逐渐增大,位错在Mg_2Si颗粒处的数量增多,应力集中急剧增大,从而导致颗粒发生破碎。Microstructure of Mg-4A1-2Si（AS42） magnesium alloy was refined by reciprocating extrusion（RE） process. Refinement effect, breaking feature, regularity of distribution and breaking mechanism of Mg2 Si particles were investigated. The results show that the particles dimension decreased constantly, the eveness and dispersity of Mg2 Si particles increased with increasing the passes of RE from as-cast to 8 passes, however the particles coarsened at RE-11 passes. The peak value of compression stress was about 75 MPa, which was greater than the fracture stress （48 MPa） of Mg2Si particles at 400℃ and strain rate of 0. 01 s^-1, resulting in the particles fractured after RE. The density and amount of the dislocation which assembled around Mg2 Si particles increased with increasing the RE passes, and the stress concentration increased rapidly that led to the particles breaking.

关 键 词：往复挤压 Mg-4Al-2Si镁合金 Mg2Si颗粒 破碎规律 

分 类 号：TG146.2[一般工业技术—材料科学与工程] TG142.1[金属学及工艺—金属材料]