Zr对Mg-Gd-Er合金晶粒细化机理的影响
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摘要
利用OM、EBSD对比分析了Zr的加入对Mg-Gd-Er合金凝固组织的影响,采用DSC测试了Mg-11Gd-2Er和Mg-11Gd-2Er-0.4Zr 2种合金熔体的过冷度,计算了Zr的加入对合金熔体润湿角及形核激活能的影响,利用HRTEM分析了Zr与Mg的界面关系及Zr的加入对界面能的影响。结果表明,Zr的加入能明显细化Mg-Gd-Er合金的晶粒尺寸,晶粒尺寸由大概率的1000 mm降到了50 mm,细化效果明显;Zr的加入使合金熔体的润湿角由18.3°降到了11.1°,熔体的形核激活能降低了44.4%;Mg的(1010)面与Zr的(1100)面完全共格,降低了Mg和Zr之间的界面能。熔体润湿角的降低和Mg与Zr的完全共格界面关系是细化Mg-Gd-Er合金晶粒尺寸的有效机制。
In recent years, Zr is widely used as an important additive element in magnesium alloys containing rare earth(RE), to improve the mechanical properties of Mg-RE alloys such as strength, ductility, creep resistance and corrosion resistance property. Heterogeneous nucleation mechanism and peritectic reaction mechanism are recognized as the main grain refining mechanisms. Whereas, during the solidification process, the melt wetting angle and nucleation energy are important factors which influence the nucleation. In this work, the effect of Zr on the solidification microstructure of the Mg-Gd-Er alloy was analyzed by using OM and EBSD; the undercooling of alloy melts was tested by using DSC; and the Mg/Zr interface relationship and interfacial energy were investigated by using HRTEM. Moreover, the effects of Zr on the wetting angle and nucleation activation energy of the Mg-11 Gd-2 Er and Mg-11 Gd-2 Er-0.4 Zr alloys were investigated; the refinement mechanism of Zr on the alloys was discussed. The results indicates that the addition of Zr element can significantly refine the grain, and the grain size decreased from 1000 mm to50 mm. Compared with the Zr-free alloy, the nucleation wetting angle of the present alloy melt decreased from 18.3° to 11.1°, and the activation energy of nucleation decreased by 44.4%. The(1010) plane of Mg was completely coherent with the(1100) plane of Zr, reducing the interfacial energy between the(1010)Mg and the(1100)Zr. The grain refinement of Mg-Gd-Er alloy was ascribed to the decrease of melt wetting angle and the fully coherent interface relationship between Mg and Zr.
In recent years, Zr is widely used as an important additive element in magnesium alloys containing rare earth(RE), to improve the mechanical properties of Mg-RE alloys such as strength, ductility, creep resistance and corrosion resistance property. Heterogeneous nucleation mechanism and peritectic reaction mechanism are recognized as the main grain refining mechanisms. Whereas, during the solidification process, the melt wetting angle and nucleation energy are important factors which influence the nucleation. In this work, the effect of Zr on the solidification microstructure of the Mg-Gd-Er alloy was analyzed by using OM and EBSD; the undercooling of alloy melts was tested by using DSC; and the Mg/Zr interface relationship and interfacial energy were investigated by using HRTEM. Moreover, the effects of Zr on the wetting angle and nucleation activation energy of the Mg-11 Gd-2 Er and Mg-11 Gd-2 Er-0.4 Zr alloys were investigated; the refinement mechanism of Zr on the alloys was discussed. The results indicates that the addition of Zr element can significantly refine the grain, and the grain size decreased from 1000 mm to50 mm. Compared with the Zr-free alloy, the nucleation wetting angle of the present alloy melt decreased from 18.3° to 11.1°, and the activation energy of nucleation decreased by 44.4%. The(1010) plane of Mg was completely coherent with the(1100) plane of Zr, reducing the interfacial energy between the(1010)Mg and the(1100)Zr. The grain refinement of Mg-Gd-Er alloy was ascribed to the decrease of melt wetting angle and the fully coherent interface relationship between Mg and Zr.
引文
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[18]Sun M,Wu G H,Wang W,et al.Effect of Zr on the microstructure,mechanical properties and corrosion resistance of Mg-10Gd-3Y magnesium alloy[J].Mater.Sci.Eng.,2009,A523:145
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[20]Qian M,Das A.Grain refinement of magnesium alloys by zirconium:formation of equiaxed grains[J].Scr.Mater.,2006,54:881
[21]Peng Z K,Zhang X M,Chen J M,et al.Grain refinement mechanism of zirconium in the Mg-9Gg-4Y alloys[J].J.Univ.Sci.Technol.Beijing,2006,28:148(彭卓凯,张新明,陈健美等.Zr在Mg-9Gd-4Y合金中的晶粒细化机制[J].北京科技大学学报,2006,28:148)
[22]Qian M,Stjohn D H,Frost M T.Characteristic zirconium-rich coring structures in Mg-Zr alloys[J].Scr.Mater.,2002,46:649
[23]Mueller B A,Perepezko J H.The undercooling of aluminum[J].Metall.Mater.Trans.,1987,18A:1143
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[25]Gao Y M.Principle of Metal Solidification[M].Xi'an:Xi'an Jiaotong University Press,2010:39(高义民.金属凝固原理[M].西安:西安交通大学出版社,2010:39)
[26]Turnbull D.Formation of crystal nuclei in liquid metals[J].J.Appl.Phys.,1999,21:1022
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[28]Jian Z Y,Chang F E,Ma W H,et al.Nucleation and undercooling of metal melt[J].Sci.China,2000,30E:9(坚增运,常芳娥,马卫红,等.金属熔体的形核和过冷度[J].中国科学,2000,30E:9)
[29]Bramfitt B.The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid Iron[J].Metall.Trans.,1970,1:1987
[2]Watanabe H,Mukai T,Ishikawa K,et al.Realization of high-strainrate superplasticity at low temperatures in a Mg-Zn-Zr alloy[J].Mater.Sci.Eng.,2001,A307:119
[3]Wang J,Yang Y S,Tong W H.Effect of purification treatment on corrosion resistance of Mg-Gd-Y-Zr alloy[J].Trans.Nonferrous Met.Soc.China,2011,21:949
[4]Wang L Y,Huang J,Dong J,et al.Microstructure evolution in the fusion zone of laser-welded Mg-Gd-Y-Zr alloy during solution and aging treatment[J].Mater.Charact.,2016,118:486
[5]Wang H,Wang Q D,Boehlert C J,et al.Tensile and compressive creep behavior of extruded Mg-10Gd-3Y-0.5Zr(wt.%)alloy[J].Mater.Charact.,2015,99:25
[6]Lu F M,Ma A B,Jiang J H,et al.Enhanced mechanical properties and rolling formability of fine-grained Mg-Gd-Zn-Zr alloy produced by equal-channel angular pressing[J].J.Alloys Compd.,2015,643:28
[7]Yin S Q,Zhang Z Q,Liu X,et al.Effects of Zn/Gd ratio on the microstructures and mechanical properties of Mg-Zn-Gd-Zr alloys[J].Mater.Sci.Eng.,2017,A695:135
[8]Zeng X Q,Wu Y J,Peng L M,et al.LPSO structure and aging phases in Mg-Gd-Zn-Zr alloy[J].Acta Metall.Sin.,2010,46:1041(曾小勤,吴玉娟,彭立明等.Mg-Gd-Zn-Zr合金中的LPSO结构和时效相[J].金属学报,2010,46:1041)
[9]Lv B J,Peng J,Peng Y,at al.The effect of LPSO phase on hot deformation behavior and dynamic recrystallization evolution of Mg-2.0Zn-0.3Zr-5.8Y alloy[J].Mater.Sci.Eng.,2013,A579:209
[10]Chen Q,Xia X S,Yuan B G,et al.Hot workfability behavior of ascast Mg-Zn-Y-Zr alloy[J].Mater.Sci.Eng.,2014,A593:38
[11]Zhang Z Q,Liu X,Wang Z K,et al.Effects of phase composition and content on the microstructures and mechanical properties of high strength Mg-Y-Zn-Zr alloys[J].Mater.Des.,2015,88:915
[12]Lan A Y,Huo L F.Effect of substitution of minor Nd for Y on mechanical and damping properties of heat-treated Mg-Zn-Y-Zr alloy[J].Mater.Sci.Eng.,2016,A651:646
[13]Xu C,Zheng M Y,Xu S W,et al.Improving strength and ductility of Mg-Gd-Y-Zn-Zr alloy simultaneously via extrusion,hot rolling and ageing[J].Mater.Sci.Eng.2015,A643:137
[14]Bettles C J,Gibson M A,Zhu S M.Microstructure and mechanical behaviour of an elevated temperature Mg-rare earth based alloy[J].Mater.Sci.Eng.,2009,A505:6
[15]Zhang S J,Li W X.The effect of Zr to the grain size and as-cast mechanical properties of magnesium alloy Mg-Ce[J].Light Alloy Fabric.Technol.,2003,31(2):16(张世军,黎文献.Zr对Mg-Ce合金的晶粒大小及铸态组织性能的影响[J].轻合金加工技术,2003,31(2):16)
[16]Liu H M,Chen Y G,Tang Y B,et al.Effect of Zr-adding on microstructure and mechanical properties for Mg-5Sn alloy[J].Rare Met.Mater.Eng.,2006,35:1912(刘红梅,陈云贵,唐永柏等.Zr对Mg-5Sn合金显微组织与力学性能的影响[J].稀有金属材料与工程,2006,35:1912)
[17]Huan Z G,Leeflang M A,Zhou J,et al.In vitro degradation behavior and cytocompatibility of Mg-Zn-Zr alloys[J]J.Mater.Sci.Mater.Med.,2010,21:2623
[18]Sun M,Wu G H,Wang W,et al.Effect of Zr on the microstructure,mechanical properties and corrosion resistance of Mg-10Gd-3Y magnesium alloy[J].Mater.Sci.Eng.,2009,A523:145
[19]Lee Y C,Dahle A K,Stjohn D H.The role of solute in grain refinement of magnesium[J].Metall.Mater.Trans.,2000,31A:2895
[20]Qian M,Das A.Grain refinement of magnesium alloys by zirconium:formation of equiaxed grains[J].Scr.Mater.,2006,54:881
[21]Peng Z K,Zhang X M,Chen J M,et al.Grain refinement mechanism of zirconium in the Mg-9Gg-4Y alloys[J].J.Univ.Sci.Technol.Beijing,2006,28:148(彭卓凯,张新明,陈健美等.Zr在Mg-9Gd-4Y合金中的晶粒细化机制[J].北京科技大学学报,2006,28:148)
[22]Qian M,Stjohn D H,Frost M T.Characteristic zirconium-rich coring structures in Mg-Zr alloys[J].Scr.Mater.,2002,46:649
[23]Mueller B A,Perepezko J H.The undercooling of aluminum[J].Metall.Mater.Trans.,1987,18A:1143
[24]Holland-Moritz D,Schroers J,Herlach D M,et al.Undercooling and solidification behaviour of melts of the quasicrystal-forming alloys Al-Cu-Fe and Al-Cu-Co[J].Acta Mater.,1998,46:1601
[25]Gao Y M.Principle of Metal Solidification[M].Xi'an:Xi'an Jiaotong University Press,2010:39(高义民.金属凝固原理[M].西安:西安交通大学出版社,2010:39)
[26]Turnbull D.Formation of crystal nuclei in liquid metals[J].J.Appl.Phys.,1999,21:1022
[27]Huang C,Song B,Mao J H,et al.The mathematical model of wetting angle of heterogeneous nucleation[J].Sci.China,2004,34E:737(黄诚,宋波,毛璟红等.非均质形核润湿角数学模型研究[J].中国科学,2004,34E:737)
[28]Jian Z Y,Chang F E,Ma W H,et al.Nucleation and undercooling of metal melt[J].Sci.China,2000,30E:9(坚增运,常芳娥,马卫红,等.金属熔体的形核和过冷度[J].中国科学,2000,30E:9)
[29]Bramfitt B.The effect of carbide and nitride additions on the heterogeneous nucleation behavior of liquid Iron[J].Metall.Trans.,1970,1:1987