非平衡凝固AZ91+0.75％Er镁合金及其热处理
Non-equilibrium Solidification of AZ91+0.75％Er Magnesium Alloy and Subsequent Heat Treatment
张燕龙 1杨伟 1周珍珍 1余欢 1蔡长春1
作者信息
- 1. 南昌航空大学轻合金加工科学与技术国防重点学科实验室,江西南昌330063
- 折叠
摘要
采用铜模喷铸技术制备出AZ91+0.75％Er(质量分数)稀土镁合金非平衡凝固试棒,研究了低温时效及高温固溶对合金组织和显微硬度的影响规律.结果表明,稀土元素的添加及冷却速率的提高均有利于细化AZ91镁合金组织,其中后者影响效果更加明显.急冷条件下的溶质截留效应还可以消除铸态稀土镁合金中的Al-Er针状化合物相.非平衡凝固合金经200℃时效处理后,β相从过饱和固溶体中析出.时效16h后,Mg-Er稀土化合物相以颗粒团聚状从基体中形成.420℃固溶处理时,非平衡凝固合金中β相发生溶解,晶粒形貌转变为多边形等轴晶组织,平均晶粒尺寸随固溶时间的延长而不断增加.非平衡凝固及后续时效处理可有效提高稀土镁合金的显微硬度,而固溶条件下合金硬度值有所降低.
Abstract
Non-equilibrium solidification samples of AZ9 l+0.75wt％Er magnesium alloy were fabricated by a copper mould spray-casting technique.The effects of aging and solid solution treatments on microstructure and micro-hardness were researched.It is shown that both the addition of rare earth element and increase of cooling rate are advantageous to the refinement of AZ91 alloy,among which the latter plays a more important role.Moreover,the solute trapping from rapid quenching eliminates the occurrence of acicular Al-Er compound.After aging at 200 ℃,β phase precipitates from the super-saturated solid solution.With increasing isothermal time to 16 h,Mg-Er phase is generated with cluster distribution.As for solution temperature of 420 ℃,the grain appears distinctly because of the dissolution of eutectic phase,and the average size of primary grain increases with extending solution time.The hardnesses of non-equilibrium solidified and aged AZ91+0.75％Er alloy are enhanced continuously in comparison to that of as-cast ingot.However,a weak reduction of hardness occurs after solution treatment.
关键词
稀土镁合金/非平衡凝固/热处理/显微硬度Key words
rare earth magnesium alloy/non-equilibrium solidification/heat treatment/micro-hardness引用本文复制引用
基金项目
国家自然科学基金(51164028)
轻合金加工科学与技术国防重点学科实验室开放课题(GF201201003)
出版年
2014
NETL
NSTL
维普
万方数据