摘要
通过OM、SEM、硬度及拉伸等测试手段,研究了EW75-0.7Al合金挤压及时效态的组织和力学性能。结果表明,挤压后合金晶粒明显细化,室温力学性能显著提高,抗拉强度为330MPa,屈服强度为242MPa,伸长率为11%。通过对合金进行T5时效处理,确定EW75-0.7Al合金的最佳T5峰时效制度为225℃×12h,经过T5峰时效处理后,合金的室温强度相比挤压态提高约100MPa。T5峰时效态合金在200℃高温下,力学性能下降不明显,在250℃高温下力学性能显著降低。通过分析合金高温下的断裂方式,发现250℃高温下,EW75-0.7Al合金的晶界强度显著降低,且时效析出相与基体的结合能力下降,最终导致合金在该温度下力学性能明显降低。
The microstructure and mechanical properties of extruded and aged state EW75-0. 7A1 alloy were investigated by OM, SEM, hardness and tensile testing methods. The results reveal that grain in the extruded alloy is refined obviously, and mechanical properties, such as tensile strength, yield strength and elongation, are improved significantly at room temperature to 330MPa, 242MPa and 11%, respectively. By observing T5 aging treatment of EW75-0.7Al alloy, the optimal T5 peak aging parameter is at 225 ℃ for 12 h. The T5 peak-aged alloy exhibits the better tensile strength than extruded alloy at room temperature, increased by approximately 100 MPa. At 200 ℃, the mechanical properties are de- creased slightly, however, they are deteriorated significantly at 250 ℃. By analyzing the fracture mode under 250 ℃, it is found that grain boundary strength of EW75-0.7Al alloy is weakened greatly, and the bonding strength between precipitation and matrix are also decreased, which are responsible for the decrease of the strength of the alloy at 250 ℃.
出处
《特种铸造及有色合金》
CAS
CSCD
北大核心
2014年第10期1039-1042,共4页
Special Casting & Nonferrous Alloys
基金
国家重点基础研究发展计划(973计划)资助项目(2013CB632202
2013CB632205)
国家自然科学基金资助项目(51204020)
"十二五"期间国家科学和技术支撑计划重点项目(2011BAE22B01)
关键词
稀土镁合金
挤压
组织分析
力学性能
Rare Earth Magnesium Alloy, Extrusion, Microstructure Analysis, Mechanical Properties
