等温处理对Mg-3Al-2Ca-2Nd组织和性能的影响
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摘要
为了研究等温处理工艺对Mg-3Al-2Ca-2Nd合金组织和性能的影响,利用XRD、OM、SEM、EDS及拉伸试验机对试样进行组织观察和性能测试。结果表明,与铸态组织相比,420℃等温处理的组织变化不明显,随着等温处理温度升高,铸态枝晶组织消失,转变为等轴晶组织且晶粒尺寸变大。在等温处理过程中,Al_(11)Nd_3相发生分解,生成热稳定性高的Al_2Nd相,而Al原子固溶到α-Mg基体中;层片状Al-Ca金属间相转变为颗粒状组织。随等温处理温度增加,硬度、抗拉强度和延伸率先增加后降低,在480℃时达到最大值,其值分别为66.3 HV、144.5 MPa和2.7%。
The microstructure and mechanical properties of Mg-3Al-2Ca-2Nd alloy as-cast and isothermal treated were studied by using XRD,OM,SEM,EDS and universal tensile testing machine.The experimental results indicate that the microstructure of Mg-3Al-2Ca-2Nd alloy isothermal treated at 420℃ changes slightly compared to that of as-cast alloy.With the increasing of isothermal treated temperature,the dendritic structure in as-cast Mg-3Al-2Ca-2Nd alloy disappears,equiaxed grains appear,and the size of grain increases in isothermal treated Mg-3Al-2Ca-2Nd alloy.The Al_(11)Nd_3 phases decompose and the Al2Nd phases with high thermal stability are produced,and the Al is dissolved into α-Mg in the process of isothermal treatment.The flake Al-Ca phases are changed into particle phases in the process of isothermal treatment.With the increasing of isothermal treated temperature,the hardness,tensile strength and elongation of Mg-3Al-2Ca-2Nd alloy increase first and then decrease,and the maximum value of hardness,tensile strength and elongation of Mg-3Al-2Ca-2Nd alloy treated at 480℃ are 66.3 HV,144.5 MPa and 2.7%,respectively.
The microstructure and mechanical properties of Mg-3Al-2Ca-2Nd alloy as-cast and isothermal treated were studied by using XRD,OM,SEM,EDS and universal tensile testing machine.The experimental results indicate that the microstructure of Mg-3Al-2Ca-2Nd alloy isothermal treated at 420℃ changes slightly compared to that of as-cast alloy.With the increasing of isothermal treated temperature,the dendritic structure in as-cast Mg-3Al-2Ca-2Nd alloy disappears,equiaxed grains appear,and the size of grain increases in isothermal treated Mg-3Al-2Ca-2Nd alloy.The Al_(11)Nd_3 phases decompose and the Al2Nd phases with high thermal stability are produced,and the Al is dissolved into α-Mg in the process of isothermal treatment.The flake Al-Ca phases are changed into particle phases in the process of isothermal treatment.With the increasing of isothermal treated temperature,the hardness,tensile strength and elongation of Mg-3Al-2Ca-2Nd alloy increase first and then decrease,and the maximum value of hardness,tensile strength and elongation of Mg-3Al-2Ca-2Nd alloy treated at 480℃ are 66.3 HV,144.5 MPa and 2.7%,respectively.
引文
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[3]甘俊雄,张帆,韩修柱,刘楚明.混合稀土对AZ80镁合金显微组织和力学性能的影响[J].兵器材料科学与工程,2015,38(1):81-85.
[4]AGHION E.,BRONFIN B.Magnesium Alloys Development Towards the 21st Century[J].Materials Science Forum,2000,350-351(1):179-281.
[5]张丁非,张红菊,兰伟,等.高强镁合金的研究进展[J].材料热处理学报,2012,33(6):1-5.
[6]JESSICA R.Terbush,NICHOLAS D.SADDOCK,J.et al.Partitioning of Solute to the Primary a-Mg Phase in Creep-Resistant Mg-Al-Ca-Based Cast Alloys[J].Metallurgical and Materials Transactions A,2010(41):2435-2442.
[7]LIU Manping,WANG Qudong,LIU Zili,et al.Behavior of MgAl-Ca Alloy During Solution Heat Treatment at 415℃[J].Journal of Materials Science Letters,2002(21):1281-1283.
[8]SADDOCK N.D.,SUZUKI A.,JONES J.W,et al.Grain-scale Creep Processes in Mg-Al-Ca base Alloys:Implications for Alloy Design[J].Scripta Materialia,2010(63):692-697.
[9]HOMMA T.,NAKAWAKI S.,KAMADO S.Improvement in Creep Property of a Cast Mg-6Al-3Ca Alloy by Mn Addition[J].Scripta Materialia,2010(63):1173-1176.
[10]张靖,冯义成,王琴,等.Ca和Nd复合合金化Mg-6Al合金显微组织和力学性能的研究[J].稀土,2016,37(4):86-90.
[11]冯义成,王琴,姜文勇,等.固溶处理对Mg-6Al-2Ca-2Nd合金组织和性能的影响[J].金属热处理,2013,38(11):26-29.
[12]冯义成,王琴,杨建辉,等.Ca对Mg-6Al-1Nd合金显微组织和性能的影响[J].哈尔滨理工大学学报,2014,19(5):10-13.
[13]HAKAMADA M,WATAZU A,SAITO N,et al.Effects of Homogenization Annealing on Dynamic Recrystallization in Mg-Al-CaRE(Rare Earth)Alloy[J].Materials Transactions,2008,49(5):1032-1037.
[14]SU M L,ZHANG J H,FENG Y,et al.Al-Nd Intermetallic Phase Stability and Its Effects on Mechanical Properties and Corrosion Resistance of HPDC Mg-4Al-4Nd-0.2Mn Alloy[J].Journal of Alloys and Compounds,2017(691):634-643.
[15]JIAO Y F,ZHANG J H,HE L L,et al.Al-RE Intermetallic Phase Stability and Effects on Corrosion Behavior in Cold-Chamber HPDC AE44 Alloy[J].Advanced Engineering Materials,2016,18(1):148-155.
[16]MASAKI S.Microstructure Development of Sand-cast AZ-type Magnesium Alloys Modified by Simultaneous Addition of Calcium and Neodymium[J].Journal of Alloys and Compounds,2008(460):619-626.
[17]SUZUKI A,SADDOCK ND,JONES JW,et al.Solidification Paths and Eutectic Intermetallic Phases in Mg-Al-Ca Ternary Alloys[J].Acta Mater,2005,53:2823-2834.
[18]刘阳力,张金玲,刘军,等.固溶时间对AZG315镁合金显微组织演变的影响及其作用机制[J].材料热处理学报,2016,37(6):49-53.
[19]李全安,陈晓亚,刘文健,等.复合添加Sm与Nd对AZ81镁合金组织和性能的影响[J].稀土,2015,36(2):37-40.
[20]邝亚飞,王泽辉,房大庆,等.时效处理对热挤压Mg-Zn(=1,3,5)-Y合金组织与力学性能的影响[J].中国稀土学报,2016,34(5):600-604.