Mg-Al系工业合金牌号的成分式解析
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摘要
Mg-Al系牌号是应用最广的镁基工业合金,但其牌号背后的成分根源一直未知,构成研发新合金的主要障碍.本文应用描述固溶体短程序结构特征的团簇共振模型,得到了Mg-Al二元固溶体的最理想化学结构单元[Al-Mg_(12)]Mg_1,然后对《the American Society for Testing Materials》手册中所有Mg-Al系工业合金牌号进行成分解析,得到相应团簇成分式,如AZ63A合金解析后的团簇成分式为[Al_(0.78)Zn_(0.16)-Mg_(12)]Mg_(1.04)Mn_(0.02),AZ81A合金解析后的团簇成分式为[Al_(0.97)Zn_(0.03)-Mg_(12)]Mg_(0.98)Mn_(0.02).再根据成分式与化学结构单元之间的误差,对比该牌号合金的力学性能,验证了该化学结构单元在Mg-Al体系中的准确性,揭示出看似复杂的工业合金牌号后面隐藏的简单成分规律,为发展Mg-Al体系合金指出了一个全新的途径.
Mg-Al alloys are the most widely used Mg-based industrial alloys, but their composition rules behind the apparent industrial specifications are largely unknown, which hinders the development of new alloys. As is well known, industrial alloys often undergo the process of a high-temperature solution treatment, and the final structures originate from the single-phase solid solution parent state. Since solid solutions are characterized by short-range chemical orders, necessarily the optimum alloy composition should be related to the presence of a certain short-range chemical structure unit. In the present paper, by introducing our cluster-resonance model for short-range-order structure description of solid solutions,a chemical structure unit of Mg-Al binary solid solution is established, [Al-Mg_(12)]Mg_1, which represents the characteristic short-range-order structure, with the bracketed part being the nearest-neighbor cluster centered by Al and shelled by12 Mg and with one glue atom Mg located between the clusters. Because of the existence of other alloying elements besides Al, a general formula [(Al, A)1-Mg_(12)]-(Mg, B) is then proposed, where A represents the elements showing a negative mixing enthalpy with Mg, while B showing a positive one. This formula is used to explain the multi-component Mg-Al industrial alloys. Based on this chemical formula, typical Mg-Al industrial alloy specifications in ASTM handbook are well explained. For instance, cast AZ63 A alloy is formulated as [Al_(0.78)Zn_(0.16)-Mg_(12)]Mg_(1.04)Mn_(0.02), cast AZ81 A as[Al_(0.97)Zn_(0.03)-Mg_(12)]Mg_(0.98)Mn_(0.02), and wrought AZ80 A as [Al_(1.02n0.03)-Mg_(12)]Mg_(0.94)Mn_(0.01). The deviations from the ideal chemical structure unit in different Mg-Al alloys are well correlated to their corresponding alloy performances. Those alloys, where the numbers of center atoms are close to ones in their cluster formulas, exhibit excellent comprehensive mechanical performances in both strength and plasticity. While the alloy with less than one center atom only shows good plastic performance with a relatively poor strength, and the one with more than one center atom shows just the reverse tendency. Among cast Mg-Al alloys, AZ81 A, whose cluster formula completely matches the stable chemical structure unit, exhibits the optimized combination of strength(275 MPa) and plasticity(elongation 15%). Among wrought Mg-Al alloys, AZ61 A and AZ80 A, whose cluster formulas show minor deviations of-0.11 and 0.05 in the center site from the ideal chemical structure unit, also have good comprehensive mechanical properties, respectively with the strengths of310 MPa and 380 MPa, and the elongations of 16% and 7%. Based on the results in the present paper, the simple composition rule behind the complex industrial alloy specifications as unveiled here, can be a powerful approach to the development of Mg-Al alloys.
Mg-Al alloys are the most widely used Mg-based industrial alloys, but their composition rules behind the apparent industrial specifications are largely unknown, which hinders the development of new alloys. As is well known, industrial alloys often undergo the process of a high-temperature solution treatment, and the final structures originate from the single-phase solid solution parent state. Since solid solutions are characterized by short-range chemical orders, necessarily the optimum alloy composition should be related to the presence of a certain short-range chemical structure unit. In the present paper, by introducing our cluster-resonance model for short-range-order structure description of solid solutions,a chemical structure unit of Mg-Al binary solid solution is established, [Al-Mg_(12)]Mg_1, which represents the characteristic short-range-order structure, with the bracketed part being the nearest-neighbor cluster centered by Al and shelled by12 Mg and with one glue atom Mg located between the clusters. Because of the existence of other alloying elements besides Al, a general formula [(Al, A)1-Mg_(12)]-(Mg, B) is then proposed, where A represents the elements showing a negative mixing enthalpy with Mg, while B showing a positive one. This formula is used to explain the multi-component Mg-Al industrial alloys. Based on this chemical formula, typical Mg-Al industrial alloy specifications in ASTM handbook are well explained. For instance, cast AZ63 A alloy is formulated as [Al_(0.78)Zn_(0.16)-Mg_(12)]Mg_(1.04)Mn_(0.02), cast AZ81 A as[Al_(0.97)Zn_(0.03)-Mg_(12)]Mg_(0.98)Mn_(0.02), and wrought AZ80 A as [Al_(1.02n0.03)-Mg_(12)]Mg_(0.94)Mn_(0.01). The deviations from the ideal chemical structure unit in different Mg-Al alloys are well correlated to their corresponding alloy performances. Those alloys, where the numbers of center atoms are close to ones in their cluster formulas, exhibit excellent comprehensive mechanical performances in both strength and plasticity. While the alloy with less than one center atom only shows good plastic performance with a relatively poor strength, and the one with more than one center atom shows just the reverse tendency. Among cast Mg-Al alloys, AZ81 A, whose cluster formula completely matches the stable chemical structure unit, exhibits the optimized combination of strength(275 MPa) and plasticity(elongation 15%). Among wrought Mg-Al alloys, AZ61 A and AZ80 A, whose cluster formulas show minor deviations of-0.11 and 0.05 in the center site from the ideal chemical structure unit, also have good comprehensive mechanical properties, respectively with the strengths of310 MPa and 380 MPa, and the elongations of 16% and 7%. Based on the results in the present paper, the simple composition rule behind the complex industrial alloy specifications as unveiled here, can be a powerful approach to the development of Mg-Al alloys.
引文
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[37]LüC,Liu T,Liu D,Jiang S,Zeng W 2012 Mater.Des.33 529
[38]Zhao D,Wang Z,Zuo M,Geng H 2014 Mater.Des.56589
[2]Cahn R W 1978 Nature 271 407
[3]Jones H 1980 Proc.R.Soc.London Ser.A 371 52
[4]Friedel J 1954 Adv.Phys.3 446
[5]Dong D D,Zhang S,Wang Z R,Dong C 2015 J.Appl.Crystallogr.48 2002
[6]Dong C,Wang Q,Qiang J B,Wang Y M,Jiang N,Han G,Li Y H,Wu J,Xia J H 2007 J.Phys.D:Appl.Phys.40 273
[7]Han G,Qiang J B,Li F W,Yuan L,Quan S G,Wang Q,Wang Y M,Dong C,H?sslerc P 2011 Acta Mater.595917
[8]Luo L J,Chen H,Wang Y M,Qiang J B,Wang Q,Dong C,H?sslerc P 2014 Philos.Mag.94 2520
[9]Dong C 1995 Scripta Metal.Mater.33 239
[10]Chen H,Wang Q,Wang Y,Qiang J,Dong C 2010 Philos.Mag.90 3935
[11]Chen H,Qiang J,Wang Q,Wang Y,Dong C 2011 Isr.J.Chem.51 1226
[12]Wang Q,Dong C,Qiang J,Wang Y 2007 Mater.Sci.Eng.A 449 18
[13]Zhu C L,Wang Q,Li F W,Li Y H,Wang Y M,Dong C,Zhang W,Inoue A 2009 J.Phys.:Conference Series(London:IOP Publishing)144 p012048
[14]Luo L,Wu J,Wang Q,Wang Y,Han G,Dong C 2010Philos.Mag.90 3961
[15]Wang Y,Wang Q,Zhao J,Dong C 2010 Scripta Mater.63 178
[16]Yuan L,Pang C,Wang Y,Wang Q,Qiang J,Dong C2010 Intermetallics 18 1800
[17]Li F W,Qiang J B,Wang Q,Wang Y M,Dong X L,Dong C,Zhu S J 2012 Intermetallics 30 86
[18]Wang Z R,Dong D D,Qiang J B,Wang Q,Wang Y M,Dong C 2013 Sci.China:Phys.Mech.56 1419
[19]Geng Y X,Han K M,Wang Y M,Qiang J B,Wang Q,Dong C,Zhang G F,Tegus O,H H?sslerc P 2015 Acta Metall.Sin.51 1017(in Chinese)[耿遥祥,韩凯明,王英敏,羌建兵,王清,董闯,张贵峰,特古斯,H?sslerc P 2015金属学报51 1017]
[20]Zhang J,Wang Q,Wang Y M,Dong C 2009 Acta Metall.Sin.45 1390(in Chinese)[张杰,王清,王英敏,董闯2009金属学报45 1390]
[21]Ma R T,Hao C P,Wang Q,Ren M F,Wang Y M,Dong C 2010 Acta Metall.Sin.46 1034(in Chinese)[马仁涛,郝传璞,王清,任明法,王英敏,董闯2010金属学报461034]
[22]Chen J X,Qiang J B,Wang Q,Dong C 2012 Acta Phys.Sin.61 046102(in Chinese)[陈季香,羌建兵,王清,董闯2012物理学报61 046102]
[23]Wang Q,Zha Q F,Liu E X,Dong C,Wang X J,Tan ZX,Ji C J 2012 Acta Metall.Sin.48 1201(in Chinese)[王清,查钱锋,刘恩雪,董闯,王学军,谭朝鑫,冀春俊2012金属学报48 1201]
[24]Wang Q,Li Q,Li X,Zhang R,Gao X,Dong C,Liaw PK 2015 Metall.Mater.Trans.A 46 3924
[25]Hong H,Wang Q,Dong C 2015 Sci.China:Mater.58355
[26]Zhang J,Wang Q,Wang Y,Li C,Wen L,Dong C 2010J.Mater.Res.25 328
[27]Zhang J,Wang Q,Wang Y M,Wen L S,Dong C 2010J.Alloys Compd.505 505
[28]Zhang J,Wang Q,Wang Y M,Wen L S,Dong C 2010J.Alloys Compd.505 179
[29]Hong H L,Wang Q,Dong C,Liaw P K 2014 Sci.Rep.4 7065
[30]Reinhard L,Sch?nfeld B,Kostorz G,Bührer W 1990Phys.Rev.B 41 1727
[31]Pang C 2015 Cluster Structure Model for BCC Substitutional Solid Solutions and the Application for Alloy Composition Design(Dalian:Dalian University of Technology)(in Chinese)[庞厰2015体心立方置换固溶体的团簇结构模型及其在合金成分设计中的应用(大连:大连理工大学)]
[32]Dong D D 2017 Composition Origin of Metallic Glasses and Solid Solution Alloys:Short-range-order Structural Unit(Dalian:Dalian University of Technology)(in Chinese)[董丹丹2017金属玻璃和固溶体合金的成分根源:近程序结构单元(大连:大连理工大学)]
[33]Takeuchi A,Inoue A 2005 Mater.Trans.46 2817
[34]Pearson W B,Villars P,Calvert L D 1985 American Society for Metals 1985 3258
[35]Fiepke J W 1992 ASM Handbook,Properties and Selection:Nonferrous Alloys and Special-Purpose Materials.
[36]Quan G Z,Ku T W,Song W J,Kang B S 2011 Mater.Des.32 2462
[37]LüC,Liu T,Liu D,Jiang S,Zeng W 2012 Mater.Des.33 529
[38]Zhao D,Wang Z,Zuo M,Geng H 2014 Mater.Des.56589