LZ61镁锂合金热变形行为及微观组织研究
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摘要
通过熔炼得到了铸态LZ61镁锂合金,对其进行了热压缩变形行为研究,分析了变形温度及应变速率对其热变形行为的影响,并建立了本构方程。结果表明,合金的应变速率敏感指数m=0.218,平均热变形激活能Q=99.21kJ/mol,合金的流变曲线均属于动态再结晶型,流变应力随着温度升高(应变速率降低)而减小。温度及应变速率对合金的动态再结晶影响显著;显微组织的变化证明了动态回复和动态再结晶的发生。铸态合金组织由α-Mg相基体及弥散分布在晶界上的β相组成。经热压缩后,在相同温度下,随着应变速率降低,组织由粗细相间的晶粒转变为细小均匀的再结晶晶粒。在同一应变速率下,随着温度升高,再结晶区域逐渐增大,晶粒明显细化。
The as-cast LZ61magnesium-lithium alloy was fabricated by smelting.The hot compressive deformation behavior and effects of deformation temperature and strain rate were analyzed.Meanwhile,the constitutive equation was established.The results show that the strain rate sensitivity index of the alloy is m=0.218,and the average hot deformation activation energy is Q=99.21kJ/mol.The rheological curves of the alloys are characterized by dynamic recrystallization,and the flow stress is decreased with increasing in temperature and decreasing in strain rate.Temperature and strain rate have a significant effect on the dynamic recrystallization of the alloy.Changes in the microstructure confirm the occurrence of dynamic recovery and dynamic recrystallization.The ascast alloy consists ofβ-phase dispersedly distributed on theα-phase matrix and grain boundaries.After thermocompression,at the same temperature,as the strain rate decreases,the microstructure is changed from heterogeneous grains to fine uniform recrystallized grains.At the same strain rate,as the temperature increase,the recrystallized region is increased gradually and the grains are refined remarkably.
The as-cast LZ61magnesium-lithium alloy was fabricated by smelting.The hot compressive deformation behavior and effects of deformation temperature and strain rate were analyzed.Meanwhile,the constitutive equation was established.The results show that the strain rate sensitivity index of the alloy is m=0.218,and the average hot deformation activation energy is Q=99.21kJ/mol.The rheological curves of the alloys are characterized by dynamic recrystallization,and the flow stress is decreased with increasing in temperature and decreasing in strain rate.Temperature and strain rate have a significant effect on the dynamic recrystallization of the alloy.Changes in the microstructure confirm the occurrence of dynamic recovery and dynamic recrystallization.The ascast alloy consists ofβ-phase dispersedly distributed on theα-phase matrix and grain boundaries.After thermocompression,at the same temperature,as the strain rate decreases,the microstructure is changed from heterogeneous grains to fine uniform recrystallized grains.At the same strain rate,as the temperature increase,the recrystallized region is increased gradually and the grains are refined remarkably.
引文
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[2]冯凯,李丹明,何成旦,等.航天用超轻镁锂合金研究进展[J].特种铸造及有色合金,2017,37(2):140-144.
[3]MORDIKE B L.Magnesium properties-applications-potential[J].Materials Science&Engineering,2001,A302(1):37-45.
[4] KAINER K U.Magnesium-Alloys and Technology[M].Gemany:Wiley-Vch Gmbh&Co,2003.
[5]秦凯伦,孙婷婷,豆昌露,等.新型铸造镁锂合金的微观组织和力学性能研究[J].科学技术创新,2018(6):8-9.
[6]孟祥瑞.镁锂合金合金化及其固态复合技术研究[D].哈尔滨:哈尔滨工程大学,2010.
[7] KALIMULLIN R K,VALUEV V V,BERDNIKOV A T.The effect of surface laser treatment on the creep of the magnesiumlithium alloy MA21[J].Metal Science&Heat Treatment,1986,28(9):668-670.
[8]李元元,张卫文,刘英,等.镁合金的发展动态和前景展望[J].特种铸造及有色合金,2004,24(1):14-17.
[9]童锐.铸造Mg-4Li-4Zn-Y合金的热变形行为研究[D].哈尔滨:哈尔滨工程大学,2015.
[10]贾玉鑫.热变形对Mg-Li-Al-Zn系合金组织及性能的影响[D].河南洛阳:河南科技大学,2014.
[11] GAI D Y,LIU J,LI Q X,et al.Influence of the hot deformation conditions on the texture evolution in Mg-8Li-5Zn-2RE alloy[J].Rare Metal Materials&Engineering,2013,42(4):673-678.
[12]刘鹏.铸造Mg-Li-Zn-Zr系镁合金组织及性能研究[D].成都:西华大学,2006.
[13]刘旭贺.超轻超塑性镁锂合金的制备及性能研究[D].哈尔滨:哈尔滨工程大学,2012.
[14] LIU J W,ZHAO Z G,LU S Q.Microstructure evolution and constitutive equation for the hot deformation of LZ91 Mg alloy[J].Catalysis Today,2017:119-125.
[15]张英,任智森,杨国英.镁锂合金的组织结构及熔炼加工[J].有色金属加工,2007,36(4):14-16.
[16]施加祥.论镁锂合金特殊性及其熔铸加工工艺[J].世界有色金属,2016(10):114-115.
[17]崔忠圻,刘北兴.金属学与热处理原理[M].哈尔滨:哈尔滨工业大学出版社,2004.
[18]李尧.金属塑性成形原理(第2版)[M].北京:机械工业出版社,2013.
[19] MCQUEEN H J.Metal forming:Industrial,mechanical computational and microstructural[J].Journal of Materials Processing Technology,1993,37(1-4):3-36.
[20] WU H Y,ZHOU G Z.Plastic anisotropy and strain-hardening behavior of Mg-6Li-1Zn alloy thin sheet at elevated temperatures[J].Journal of Materials Science,2009,44(22):6 182-6 186.
[21]巫瑞智,张景怀,尹冬松.先进镁合金制备与加工技术[M].北京:科学出版社,2012.
[22]刘楚明,刘子娟,朱秀荣,等.镁及镁合金动态再结晶研究进展[J].中国有色金属学报,2006,16(1):1-12.