电磁搅拌下AZ91镁合金的显微组织与性能研究
|
摘要
镁合金具有密度小,电子屏蔽能力强,阻尼减震性能好,机械加工方便,使其在汽车、电子、航空等领域获得了越来越广泛的应用。但镁合金的应用远不及其它主要金属材料,造成这种现状的主要原因在于镁合金材料自身的强度低、脆性大、耐蚀性差和高温性能差等原因。因此,通过晶粒细化的方法,积极探索改善镁合金的力学性能和成形性能的途径,对于推动镁合金材料的应用并发挥其性能优势具有重要意义。
本文以目前使用最广泛的AZ91镁合金为对象,研究了电磁搅拌和合金元素Ce、Sr、Ca的复合作用对其显微组织及性能的影响,并对其组织细化机理进行了探讨。采用金相显微镜、扫描电子显微镜和X射线衍射仪等对合金的组织结构进行了观察与分析,测量了合金晶粒尺寸及硬度值,并对两者之间的关系进行了回归分析。结果表明:电磁搅拌和合金元素的复合作用都能明显细化铸态AZ91镁合金合金组织。在100V电磁搅拌电压的条件下,分别加入0.2%～0.8%Ce、0.1%～0.3%Sr和0.1%～0.3%Ca,当Ce、Ca、Sr的含量分别为0.8%、0.2%和0.2%时合金晶粒尺寸最小,硬度值最大。回归分析表明,晶粒尺寸与硬度之间的关系符合Hall-petch公式。此外,利用差热分析探讨了电磁搅拌和Ce、Sr、Ca对AZ91镁合金的晶粒细化机制,晶粒细化可归结于合金过冷度的减小。
利用静态失重法、X射线衍射仪和能谱分析仪研究了电磁搅拌和Ce、Sr、Ca复合处理对AZ91镁合金在3.5%NaCl水溶液中的腐蚀规律。结果表明,电磁搅拌和0.2%～0.8%Ce的加入可显著降低基体合金的腐蚀速度,在电磁搅拌电压为100V条件下,加入0.5%Ce时合金的腐蚀速度降低幅度最大。电磁搅拌与0.1%～0.3%Sr的复合作用也可改善合金的腐蚀性能,其作用不及稀土元素Ce。0.1%～0.3%Ca元素的加入对合金的腐蚀性能产生不利影响。
Magnesium alloys are widely used in automotive,electric and aeronautical industries due to their low density,good electromagnetic shielding characteristics, high damping characteristics,excellent machinability and so on.However,the application of magnesium alloys is far less than other metal materials because of its inherent properties,,such as.lower strength,poor corrosion resistance and high-temperature performance and so on.Therefore,it is important to explore active approach of improving the mechanical properties and formability through grain refinement,thus to push the application of magnesium alloys and develop theirs performance,advantages.
In this thesis,the effect of combined electromagnetic stirring and Ce,Sr,Ca on microstructure and performance of AZ91 magnesium alloy,which is the most widely used magnesium alloy,was studied.As well as grain refinement mechanism of alloys was discussed.Microstructures of alloys were observed by means of optical microscope(OM),scanning electron microscope(SEM)and X-ray diffract analyzer (XRD)and so on.Meanwhile,the grain size and hardness of alloys was measured,the linear relation was presented between grain size and hardness by regression analysis. The experimental results show that the effect of combined electromagnetic stirring and Ce,Sr,Ca caused a large decrease of grain size.In the case of 100V electromagnetic stirring voltage,when the content of Ce,Ca,Sr was 0.8%、0.2wt%、0.2wt%,respectively,the refine effect of AZ91D alloy was best as well as the highest hardness vaule after the addintion of 0.2%～0.8%Ce,0.1%～0.3%Sr,0.1%～0.3%Ca. Regression analysis reveals that the relation of between grain size and hardness is in coincidence with Hall-petch formual.Besides,the grain refinement mechanism of combined electromagnetic stirring and Ce,Sr,Ca was attributed to the decrease of undercooling degree of alloys according to differential thermal analysis results。
The effect of combined electromagnetic stirring and Ce,Sr,Ca on corrosion perfomance in 3.5%NaCl solution were studied by means of static weight-loss test, X-ray diffract analyzer and energy spectrum analysis.The experiment indicates that the additions of 0.2%～0.8%Ce and 0.1%～0.3%Sr were benefit to improve the corrosion resistance of AZ91 alloy with electromagnetic stirring,which the improvement of corrosion resistance of the addition Sr is inferior to that of Ce.And when the content of Ce was 0.5%,the corrosion resistance was best.However,the additions of Ca deteriorated its corrosion resistance.
本文以目前使用最广泛的AZ91镁合金为对象,研究了电磁搅拌和合金元素Ce、Sr、Ca的复合作用对其显微组织及性能的影响,并对其组织细化机理进行了探讨。采用金相显微镜、扫描电子显微镜和X射线衍射仪等对合金的组织结构进行了观察与分析,测量了合金晶粒尺寸及硬度值,并对两者之间的关系进行了回归分析。结果表明:电磁搅拌和合金元素的复合作用都能明显细化铸态AZ91镁合金合金组织。在100V电磁搅拌电压的条件下,分别加入0.2%～0.8%Ce、0.1%～0.3%Sr和0.1%～0.3%Ca,当Ce、Ca、Sr的含量分别为0.8%、0.2%和0.2%时合金晶粒尺寸最小,硬度值最大。回归分析表明,晶粒尺寸与硬度之间的关系符合Hall-petch公式。此外,利用差热分析探讨了电磁搅拌和Ce、Sr、Ca对AZ91镁合金的晶粒细化机制,晶粒细化可归结于合金过冷度的减小。
利用静态失重法、X射线衍射仪和能谱分析仪研究了电磁搅拌和Ce、Sr、Ca复合处理对AZ91镁合金在3.5%NaCl水溶液中的腐蚀规律。结果表明,电磁搅拌和0.2%～0.8%Ce的加入可显著降低基体合金的腐蚀速度,在电磁搅拌电压为100V条件下,加入0.5%Ce时合金的腐蚀速度降低幅度最大。电磁搅拌与0.1%～0.3%Sr的复合作用也可改善合金的腐蚀性能,其作用不及稀土元素Ce。0.1%～0.3%Ca元素的加入对合金的腐蚀性能产生不利影响。
Magnesium alloys are widely used in automotive,electric and aeronautical industries due to their low density,good electromagnetic shielding characteristics, high damping characteristics,excellent machinability and so on.However,the application of magnesium alloys is far less than other metal materials because of its inherent properties,,such as.lower strength,poor corrosion resistance and high-temperature performance and so on.Therefore,it is important to explore active approach of improving the mechanical properties and formability through grain refinement,thus to push the application of magnesium alloys and develop theirs performance,advantages.
In this thesis,the effect of combined electromagnetic stirring and Ce,Sr,Ca on microstructure and performance of AZ91 magnesium alloy,which is the most widely used magnesium alloy,was studied.As well as grain refinement mechanism of alloys was discussed.Microstructures of alloys were observed by means of optical microscope(OM),scanning electron microscope(SEM)and X-ray diffract analyzer (XRD)and so on.Meanwhile,the grain size and hardness of alloys was measured,the linear relation was presented between grain size and hardness by regression analysis. The experimental results show that the effect of combined electromagnetic stirring and Ce,Sr,Ca caused a large decrease of grain size.In the case of 100V electromagnetic stirring voltage,when the content of Ce,Ca,Sr was 0.8%、0.2wt%、0.2wt%,respectively,the refine effect of AZ91D alloy was best as well as the highest hardness vaule after the addintion of 0.2%～0.8%Ce,0.1%～0.3%Sr,0.1%～0.3%Ca. Regression analysis reveals that the relation of between grain size and hardness is in coincidence with Hall-petch formual.Besides,the grain refinement mechanism of combined electromagnetic stirring and Ce,Sr,Ca was attributed to the decrease of undercooling degree of alloys according to differential thermal analysis results。
The effect of combined electromagnetic stirring and Ce,Sr,Ca on corrosion perfomance in 3.5%NaCl solution were studied by means of static weight-loss test, X-ray diffract analyzer and energy spectrum analysis.The experiment indicates that the additions of 0.2%～0.8%Ce and 0.1%～0.3%Sr were benefit to improve the corrosion resistance of AZ91 alloy with electromagnetic stirring,which the improvement of corrosion resistance of the addition Sr is inferior to that of Ce.And when the content of Ce was 0.5%,the corrosion resistance was best.However,the additions of Ca deteriorated its corrosion resistance.
引文
[1]Polmear I J.Magnesium alloys and applications[J].Mater Sci Tech,1994,(1):1-16
[2]Cahn R W,丁道云译.非铁合金的结构与性能[M].北京:科学出版社,1999.
[3]刘正,张奎,曾小勤.镁基轻质合金理论基础及应用[M].北京:机械工业出版社,2002
[4]曾荣昌,柯伟,徐永波.Mg合金的最新发展及应用前景[J].金属学报,2001,(7):673-685
[5]师昌绪,李恒德,王定佐.加速我国金属镁工业发展的建议[J].材料导报,2001,(4):5-6
[6]Mordike B.L,Ebert T.Magnesium-properties-application-potential[J].Materials Science and Engineering,2001,A302:37-45
[8]Robert E.Sinomag.Die casting magnesium seminar[J].Light Metal Age,2001,(1):92-97
[9]Edward J.Vinarcik.Light metal advances in the automotive industry[J].Light Metal Age,2001,(4):74-77
[10]刘正,王越,王中光.镁基轻质材料的研究与应用[J].材料研究学报,2000,14(6):449-456
[11]Dwain M.Magers.A Global Review of Magnesium Parts in Automobiles[J].Light Metal Age,1996,(5):60-62
[12]Frieclrich H,Schumann S.Research for A "New Age of Magnesium" in the Automotive industry[J].Journal of Materials Processing Technology,2001,(117):276-281
[13]Luo A,Pekgnleruzm O.Cast magnesium alloys for elevated temperature application[J].J Mater Sci,1994,(29):5259-5271
[14]Aghion E,Bronfin B.Magnesium Alloys Development Toward the 21st Century[J].Materials Science Forum,2000,(351):19-28
[15]David H StJohn,Ma Qian,Mark A Easton et al.Grain Refinement of Magnesium Alloys[J].Metallurgical and Materials Transactions,2005,36A:1669-1679
[16]Kinji Hirai,Hidetoshi Somekawa,Yorinobu Takigawa.Effects of Ca and Sr addition on mechanical properties of a cast AZ91 magnesium alloy at room and elevated temperature[J].Materials Science and Engineering,2005,A403:276-280
[17]Rokhlin L L,Nikitina N I.Effect of calcium on the properties of the Mg-Al system[J].Metal Science and Heat Treatment,2003,45(5-6):171-173
[6]Li P J,Tang B,Kandalova E G.Microstructure and properties of AZ91D alloy with Ca additions[J].Materials Letters,2005,59:671- 675
[18]Flemings M C.Behavior of metal alloys in the semi-solid state[J].Metall Trans,1991,22B(6):269-293
[19]Lee Y C,Dahle A K,Stjohn D H.The role of solute in grain refinement of magnesium[J].Metall Mater Trans A,2000,(31):2895-2906
[20]Bamberger M.Structural refinement of cast magnesium alloys[J].Mater Sci Tech,2001,(1):15-24
[21]Tamura Y,Kono N,Motigi T,et al.Grain refinement of cast Mg-Al alloys[J].Japan institute of Light Metals,1998,48(4):395-399
[22]Yano E.Effect of pure carbon powder on grain refining of cast magnesium alloy AZ91[J].Japan institute of light metals,2001,(11):599-604
[23]Kubota K.Review processing and mechanical properties of fine-grained magnesium alloys [J].Mater Sci,1999,(34):2255-2262
[24]Wei L Y.The intergranular microstructure of cast Mg-Zn and Mg-Zn-rare earth alloys[J].Metall Mater Trans.A,1995,26A(8):1947-1956
[25]Luo A,Pekguleryuz M O.Solidification Processing and Microstructure of Cast Magnesium MMCs[J].AFS Trans.2000,94-96:313-320
[26]Luo A.DEVELOPMENT OF MATRIX GRAIN STRUCTURE DURING THE SOLIDIFICATION OF A Mg(AZ91)/SiCp COMPOSITE[J].Scripta Metallurgica et Materialia,1994,31(9):1253-1258
[27]Luo A.HETEROGENEOUS NUCLEATION AND GRAIN REFINEMENT IN CAST Mg(AZ91)/SiCp METAL MATRIX COMPOSITES.Canadian Metallurgical Quarterly,1996,35(4):375-383
[28]毛卫民,李树索,赵爱民.电磁搅拌Al-24%Si合金的显微组织[J].中国有色金属学报,2001,11(5):819-823
[29]齐雅丽,贾光霖,赵玉华.电磁搅拌对铸锭凝固组织的影响[J].沈阳航空工业学院学报,2004,21(2):17-18
[30]Griffiths W D,McCartney D G.The effect of electromagnetic stirring on macrostructure and macrosegregation in the aluminum alloy 7150[J].Materials Science and Engineering,1997,A222:140-148
[31]Mao Weimin,LI Yanjun,Zhao Aimin,et al.The formation mechanism of non-dendritic primary α-Al phase in semi-solid AlSi7Mg Alloy[J].Science and Technology of Advanced Materials,2001,2:97-99
[32]Ravi Kumar N V,Blandan J J,Desrayaud C,et al.Grain Refinemengt in AZ91 Magnesium Alloy during Thmomechanical Processing[J].Materials and Engineering,2003,(A359):150-157
[33]Zenji Horita,Takayoshi Fajinami,Langdon T G.The potential for Scaling ECAP:Effect of Sample Refinement and Mechanical Properties[J].Materials Science and Engineering,2001,(A318):34-41
[34]Bowen J R,Gholinia A,Roberts S M.Analysis of the Billet Deformation Behavior in Equal Channel Angular Extrusion[J].Materials Science and Engineering,2000,(A287):87-99
[35]Yamashita A,Horita I,Langdon T G.Improving the Mechanical Properties of Magnesium and A Magnesium Alloy through Severe Plastic Deformation[J].Materials Science and Engineering,2001,(A300):142-147
[36]Tamura Y.Grain refining mechanism and casting structure of Mg-Zr alloy[J].Japan institute of Light Metals,1998,48(8):185-189
[37]张诗昌,魏伯康,林汉同等.钇及铈镧混合稀土对AZ91镁合金铸态组织的影响[J].中国有色金属学报,2001,11(2):99-102
[38]Wang Qu-dong,Lu Yi-zhen,Zheng Xiao-qin.Effect of RE on microstructure and properties of AZ91 magnesium alloy[J].Trans Nonferrous Met Soc China,2000,(2):235-239
[39]Chang S Y.Mechanical properties and structure of ignition-proof Mg-Ca-Zr alloys produced by squeeze casting[J].Mater Trans,JIM,1997,38(6):526-535
[40]Luo A,Pekguleryuz M O.Review cast magnesium alloys for elevated temperature application[J].J Mater Sci,1992,(29):5259-5271
[41]Nair K S,Mittal M C.Rare earths in magnesium alloys[J].Mater.Sci.Forum,1988,(30):89-104
[42]Wei L Y.The solidification behavior of Mg-Al-Rare earth alloys[J].J Alloys and Compounds,1996,(232):264-268
[43]Li Y,Jones H.Effect of rare earth and silicon additions on structure and properties of melt spun Mg-9Al-1Zn alloy[J].Mater Sci Tech,1996,12(8):651-666
[44]Wei L Y.Development of Misconstrue in cast Mg-Al-Rare earth alloys[J].Mater Sci Tech,1996,(12):741-750
[45]Pettersen G.Microstrcture of a pressure die cast magnesium-4wt%aluminium alloy modified with rare earth additions[J].Mater Sci.Eng,1996,A207:115-120
[46]王渠东,吕宜振,曾小勤.稀土在铸造镁合金中的应用[J].特种铸造及有色合金,1999(1):40-43
[47]焦众生,邢书明,刘金香,等.电磁搅拌法制备钢铁材料半固态浆料的问题与对策[J].铸造,2004,53(8):579-582
[48]袁晓光,刘正,许沂.电磁铸造对AZ91D合金组织及力学性能的影响[J].中国有色金属学报,2002,12(4):784-789
[49]翟春生,许光明,崔建忠.镁合金电磁铸造中搅拌频率的确定[J].轻合金加工技术,2003,31(2):12-15
[50]毛卫民,甄子胜,陈洪涛.电磁搅拌对半固态AZ91D镁合金组织的影响[J].材料研究学报,2005,19(3):304-309
[51]Charles Vives.Crystallization of aluminum alloys in the presence of vertical electromagnetic force fields[J].Journal of Crystal Growth,1997,173:541-549
[52]Griffiths W D,McMartney D G.The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys[J].Materials Science and Engineering,1996,A216:47-60
[53]Lee S,Lee S H,Kim D H.Effect of Y,Sr,Nd additions on the microstructure and microstructure mechanism of squeeze-cast AZ91-X magnesium alloys[J].Metal Trans,1998,29A(4):1221-1235
[54]Aliravci C A,Gruzleski J E,Dimayuga F C.Effect of strontium on the shrinkage microporosity in magnesium sand castings[J].AFS Trans,1992,(115):353-362
[55]Eivind O,Geir B F,Rosenqvist T,et al.The effect of Sr addition on the hydrogen solubility and hydride formation in pure Mg and the alloy AZ91[J].Scand J Metall,1998,(27): 133-140
[56]Kim J M,Kim K T,Jung W J.Effects of isothermal heating procedure and strontium addition on semisolid forming of AZ91 magnesium alloy[J].Mater Sci.Tech,2002,(18):698-701
[57]Gruzleski J E,Aliravci C A.US Pat[P].No 5143564,1992
[58]Mihriban O,Pekguleryuz,Eric Baril.Creep resistant magnesium diecasting alloys based on alkaline earth elements[J].Mater Trans,JIM,2001,42(7):1258-1267
[59]Sakamoto M,Akiyama S.Suppression of ignition and burning of molten Mg alloys by Ca bearing stable oxide film[J].J Mater Sci.Lett.,1997(16):1048-1052
[60]You B S,Park W W,Chung I S.The effect of calcium addition to magnesium on the microstructure and compositional changes of oxide film formed at high temperature[J].Mater Trans,JIM,2001,42(6):1139-1141
[61]Ninomiya R,Ojtro T,Kubpta K.Improved heat resistance of Mg-Al alloys by the Ca addition[J].Acta Metall Mater,1995,43(2):669-674
[62]Luo A.A new magnesium alloys for automotive powertrain applications[J].J Mater Manu SAE Trans,1998,(107):86-94
[63]James E,Hillis.The Effects of Heavy Meatal Contamination on Magnesium Corrosion Performance[J].Light Metal Age,1983,(3):25-29
[64]Song G L,Atrens A.Corrosion mechanisms of magnesium alloys.Advanced Engineering Materials,1999,1(1):11-19
[65]Chan W M,Cheng F T,Leung L K,et al.Corrosion Behavior of Magnesium Alloys AZ91and its MMC in NaCl Solution[J].Corrosion Reviews,1998,16(1-2):43-55
[66]Nakatsugawa I,Kamado S,Kojima Y.Corrosion of Magnesium Alloys Containing Rare Earth Elements[J].Corrosion Reviews,1998,16(1-2):139-147
[67]Guangling Song,Andrej Atrens,Xiangliang Wu.Corrosion Behavior of AZ21,AZ51 and AZ91 in Sodium Chloride[J].Corrsion Science,1998,(10):1769-1791
[68]虞觉奇,易文质.二元合金状态图集[M].上海:上海科学技术出版社,1987
[69]Coriell S R,Mcfadden G B,Billia B,Thi H N,Dabo Y.Electrical pulsing during directional solidification:analysis of transients by Laplace transform[J],Journal of Crystal Growth, 2000,216:495-500.
[70]Hjellming L N,Tolley P A,Walker J S.Melt motion in a Czochralski crystal puller with a non-uniform axisymmetric magnetic field:isothermal motion[J].Journal of Fluid Mechanics,1993,249:1-34
[71]Bessaih R,Kadja M,Marry P.Effect of wall electrical conductivity and magnetic field orientation on liquid metal flow in a geometry similar to the horizontal Bridgman configuration for crystal growth[J].International Journal of Heat and Mass Transfer,1999,42:4345-4362.
[72]Geiger G H,Pokier D R.Transport Phenomena in Metallurgy[M].AddisonWesley publishing company,1973,85-86
[73]尚晓江,等.ANSYS结构有限元高级分析方法与范例应用[M].北京:中国水利水电出版社,2006
[74]李文彬.磁力应用工程[M].北京:兵器工业出版社,1991
[75]Charles Vives.Crystallization of aluminum alloys in the presence of vertical electromagnetic force fields[J].Journal of Crystal Growth,1997,173:541-549
[76]Griffiths W D,McMartney D G.The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys[J].Materials Science and Engineering,1996,A216:47-60
[77]王学东,时海芳,张伟强,等.电磁搅拌Al-Si合金宏观组织细化机理[J].辽宁工程技术大学学报,2000,19(4):430-432
[78]周永欣,谢辉,吕振林.电磁搅拌对铝硅合金显微组织的影响[J].铸造技术,2003,24(3):199-201
[79]坚增运,常芳娥,马卫宏.金属熔体的形核和过冷度[J].中国科学[E]:2000,30(1):9-12
[80]刘国勋.金属学原理[M].北京:冶金工业出版社,1980
[81]胡汉起.金属凝固原理[M].北京:机械工业出版社,2000
[82]Jung B I,Jung C H,Hart T K,et al.Electromagnetic stirring and Sr modification in A356alloy[J].Journal of Materials Processing Technology,2001,111:69-73
[83]黄明志,石德珂,金志浩.金属力学性能[M].西安:西安交通大学出版社,1986
[84]哈富宽.金属力学性质的微观理论[M].北京:科学出版社
[85]周尧和,胡状麒,介万奇.凝固技术[M].北京:机械工业出版社,1998
[86]Dahle A K,Lee Y C,Mark D N.Development of the as-cast microstructure in magnesium-aluminium alloys[J].J Light Metals,2001,(1):61-72
[87]Guangling Song,Andrej Atrens,Matthew Dargusch.Influence of Microstructure on the corrosion of Die Cast AZ91D[J].Corrosion Science,1999,(41):249-273
[88]Liu X,Xiang Y,Wang Q,Ding W.Corrosion control technologies for magnesium alloys[J].Corrosion Science and Protection Technology,2001,13(4):211-223
[2]Cahn R W,丁道云译.非铁合金的结构与性能[M].北京:科学出版社,1999.
[3]刘正,张奎,曾小勤.镁基轻质合金理论基础及应用[M].北京:机械工业出版社,2002
[4]曾荣昌,柯伟,徐永波.Mg合金的最新发展及应用前景[J].金属学报,2001,(7):673-685
[5]师昌绪,李恒德,王定佐.加速我国金属镁工业发展的建议[J].材料导报,2001,(4):5-6
[6]Mordike B.L,Ebert T.Magnesium-properties-application-potential[J].Materials Science and Engineering,2001,A302:37-45
[8]Robert E.Sinomag.Die casting magnesium seminar[J].Light Metal Age,2001,(1):92-97
[9]Edward J.Vinarcik.Light metal advances in the automotive industry[J].Light Metal Age,2001,(4):74-77
[10]刘正,王越,王中光.镁基轻质材料的研究与应用[J].材料研究学报,2000,14(6):449-456
[11]Dwain M.Magers.A Global Review of Magnesium Parts in Automobiles[J].Light Metal Age,1996,(5):60-62
[12]Frieclrich H,Schumann S.Research for A "New Age of Magnesium" in the Automotive industry[J].Journal of Materials Processing Technology,2001,(117):276-281
[13]Luo A,Pekgnleruzm O.Cast magnesium alloys for elevated temperature application[J].J Mater Sci,1994,(29):5259-5271
[14]Aghion E,Bronfin B.Magnesium Alloys Development Toward the 21st Century[J].Materials Science Forum,2000,(351):19-28
[15]David H StJohn,Ma Qian,Mark A Easton et al.Grain Refinement of Magnesium Alloys[J].Metallurgical and Materials Transactions,2005,36A:1669-1679
[16]Kinji Hirai,Hidetoshi Somekawa,Yorinobu Takigawa.Effects of Ca and Sr addition on mechanical properties of a cast AZ91 magnesium alloy at room and elevated temperature[J].Materials Science and Engineering,2005,A403:276-280
[17]Rokhlin L L,Nikitina N I.Effect of calcium on the properties of the Mg-Al system[J].Metal Science and Heat Treatment,2003,45(5-6):171-173
[6]Li P J,Tang B,Kandalova E G.Microstructure and properties of AZ91D alloy with Ca additions[J].Materials Letters,2005,59:671- 675
[18]Flemings M C.Behavior of metal alloys in the semi-solid state[J].Metall Trans,1991,22B(6):269-293
[19]Lee Y C,Dahle A K,Stjohn D H.The role of solute in grain refinement of magnesium[J].Metall Mater Trans A,2000,(31):2895-2906
[20]Bamberger M.Structural refinement of cast magnesium alloys[J].Mater Sci Tech,2001,(1):15-24
[21]Tamura Y,Kono N,Motigi T,et al.Grain refinement of cast Mg-Al alloys[J].Japan institute of Light Metals,1998,48(4):395-399
[22]Yano E.Effect of pure carbon powder on grain refining of cast magnesium alloy AZ91[J].Japan institute of light metals,2001,(11):599-604
[23]Kubota K.Review processing and mechanical properties of fine-grained magnesium alloys [J].Mater Sci,1999,(34):2255-2262
[24]Wei L Y.The intergranular microstructure of cast Mg-Zn and Mg-Zn-rare earth alloys[J].Metall Mater Trans.A,1995,26A(8):1947-1956
[25]Luo A,Pekguleryuz M O.Solidification Processing and Microstructure of Cast Magnesium MMCs[J].AFS Trans.2000,94-96:313-320
[26]Luo A.DEVELOPMENT OF MATRIX GRAIN STRUCTURE DURING THE SOLIDIFICATION OF A Mg(AZ91)/SiCp COMPOSITE[J].Scripta Metallurgica et Materialia,1994,31(9):1253-1258
[27]Luo A.HETEROGENEOUS NUCLEATION AND GRAIN REFINEMENT IN CAST Mg(AZ91)/SiCp METAL MATRIX COMPOSITES.Canadian Metallurgical Quarterly,1996,35(4):375-383
[28]毛卫民,李树索,赵爱民.电磁搅拌Al-24%Si合金的显微组织[J].中国有色金属学报,2001,11(5):819-823
[29]齐雅丽,贾光霖,赵玉华.电磁搅拌对铸锭凝固组织的影响[J].沈阳航空工业学院学报,2004,21(2):17-18
[30]Griffiths W D,McCartney D G.The effect of electromagnetic stirring on macrostructure and macrosegregation in the aluminum alloy 7150[J].Materials Science and Engineering,1997,A222:140-148
[31]Mao Weimin,LI Yanjun,Zhao Aimin,et al.The formation mechanism of non-dendritic primary α-Al phase in semi-solid AlSi7Mg Alloy[J].Science and Technology of Advanced Materials,2001,2:97-99
[32]Ravi Kumar N V,Blandan J J,Desrayaud C,et al.Grain Refinemengt in AZ91 Magnesium Alloy during Thmomechanical Processing[J].Materials and Engineering,2003,(A359):150-157
[33]Zenji Horita,Takayoshi Fajinami,Langdon T G.The potential for Scaling ECAP:Effect of Sample Refinement and Mechanical Properties[J].Materials Science and Engineering,2001,(A318):34-41
[34]Bowen J R,Gholinia A,Roberts S M.Analysis of the Billet Deformation Behavior in Equal Channel Angular Extrusion[J].Materials Science and Engineering,2000,(A287):87-99
[35]Yamashita A,Horita I,Langdon T G.Improving the Mechanical Properties of Magnesium and A Magnesium Alloy through Severe Plastic Deformation[J].Materials Science and Engineering,2001,(A300):142-147
[36]Tamura Y.Grain refining mechanism and casting structure of Mg-Zr alloy[J].Japan institute of Light Metals,1998,48(8):185-189
[37]张诗昌,魏伯康,林汉同等.钇及铈镧混合稀土对AZ91镁合金铸态组织的影响[J].中国有色金属学报,2001,11(2):99-102
[38]Wang Qu-dong,Lu Yi-zhen,Zheng Xiao-qin.Effect of RE on microstructure and properties of AZ91 magnesium alloy[J].Trans Nonferrous Met Soc China,2000,(2):235-239
[39]Chang S Y.Mechanical properties and structure of ignition-proof Mg-Ca-Zr alloys produced by squeeze casting[J].Mater Trans,JIM,1997,38(6):526-535
[40]Luo A,Pekguleryuz M O.Review cast magnesium alloys for elevated temperature application[J].J Mater Sci,1992,(29):5259-5271
[41]Nair K S,Mittal M C.Rare earths in magnesium alloys[J].Mater.Sci.Forum,1988,(30):89-104
[42]Wei L Y.The solidification behavior of Mg-Al-Rare earth alloys[J].J Alloys and Compounds,1996,(232):264-268
[43]Li Y,Jones H.Effect of rare earth and silicon additions on structure and properties of melt spun Mg-9Al-1Zn alloy[J].Mater Sci Tech,1996,12(8):651-666
[44]Wei L Y.Development of Misconstrue in cast Mg-Al-Rare earth alloys[J].Mater Sci Tech,1996,(12):741-750
[45]Pettersen G.Microstrcture of a pressure die cast magnesium-4wt%aluminium alloy modified with rare earth additions[J].Mater Sci.Eng,1996,A207:115-120
[46]王渠东,吕宜振,曾小勤.稀土在铸造镁合金中的应用[J].特种铸造及有色合金,1999(1):40-43
[47]焦众生,邢书明,刘金香,等.电磁搅拌法制备钢铁材料半固态浆料的问题与对策[J].铸造,2004,53(8):579-582
[48]袁晓光,刘正,许沂.电磁铸造对AZ91D合金组织及力学性能的影响[J].中国有色金属学报,2002,12(4):784-789
[49]翟春生,许光明,崔建忠.镁合金电磁铸造中搅拌频率的确定[J].轻合金加工技术,2003,31(2):12-15
[50]毛卫民,甄子胜,陈洪涛.电磁搅拌对半固态AZ91D镁合金组织的影响[J].材料研究学报,2005,19(3):304-309
[51]Charles Vives.Crystallization of aluminum alloys in the presence of vertical electromagnetic force fields[J].Journal of Crystal Growth,1997,173:541-549
[52]Griffiths W D,McMartney D G.The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys[J].Materials Science and Engineering,1996,A216:47-60
[53]Lee S,Lee S H,Kim D H.Effect of Y,Sr,Nd additions on the microstructure and microstructure mechanism of squeeze-cast AZ91-X magnesium alloys[J].Metal Trans,1998,29A(4):1221-1235
[54]Aliravci C A,Gruzleski J E,Dimayuga F C.Effect of strontium on the shrinkage microporosity in magnesium sand castings[J].AFS Trans,1992,(115):353-362
[55]Eivind O,Geir B F,Rosenqvist T,et al.The effect of Sr addition on the hydrogen solubility and hydride formation in pure Mg and the alloy AZ91[J].Scand J Metall,1998,(27): 133-140
[56]Kim J M,Kim K T,Jung W J.Effects of isothermal heating procedure and strontium addition on semisolid forming of AZ91 magnesium alloy[J].Mater Sci.Tech,2002,(18):698-701
[57]Gruzleski J E,Aliravci C A.US Pat[P].No 5143564,1992
[58]Mihriban O,Pekguleryuz,Eric Baril.Creep resistant magnesium diecasting alloys based on alkaline earth elements[J].Mater Trans,JIM,2001,42(7):1258-1267
[59]Sakamoto M,Akiyama S.Suppression of ignition and burning of molten Mg alloys by Ca bearing stable oxide film[J].J Mater Sci.Lett.,1997(16):1048-1052
[60]You B S,Park W W,Chung I S.The effect of calcium addition to magnesium on the microstructure and compositional changes of oxide film formed at high temperature[J].Mater Trans,JIM,2001,42(6):1139-1141
[61]Ninomiya R,Ojtro T,Kubpta K.Improved heat resistance of Mg-Al alloys by the Ca addition[J].Acta Metall Mater,1995,43(2):669-674
[62]Luo A.A new magnesium alloys for automotive powertrain applications[J].J Mater Manu SAE Trans,1998,(107):86-94
[63]James E,Hillis.The Effects of Heavy Meatal Contamination on Magnesium Corrosion Performance[J].Light Metal Age,1983,(3):25-29
[64]Song G L,Atrens A.Corrosion mechanisms of magnesium alloys.Advanced Engineering Materials,1999,1(1):11-19
[65]Chan W M,Cheng F T,Leung L K,et al.Corrosion Behavior of Magnesium Alloys AZ91and its MMC in NaCl Solution[J].Corrosion Reviews,1998,16(1-2):43-55
[66]Nakatsugawa I,Kamado S,Kojima Y.Corrosion of Magnesium Alloys Containing Rare Earth Elements[J].Corrosion Reviews,1998,16(1-2):139-147
[67]Guangling Song,Andrej Atrens,Xiangliang Wu.Corrosion Behavior of AZ21,AZ51 and AZ91 in Sodium Chloride[J].Corrsion Science,1998,(10):1769-1791
[68]虞觉奇,易文质.二元合金状态图集[M].上海:上海科学技术出版社,1987
[69]Coriell S R,Mcfadden G B,Billia B,Thi H N,Dabo Y.Electrical pulsing during directional solidification:analysis of transients by Laplace transform[J],Journal of Crystal Growth, 2000,216:495-500.
[70]Hjellming L N,Tolley P A,Walker J S.Melt motion in a Czochralski crystal puller with a non-uniform axisymmetric magnetic field:isothermal motion[J].Journal of Fluid Mechanics,1993,249:1-34
[71]Bessaih R,Kadja M,Marry P.Effect of wall electrical conductivity and magnetic field orientation on liquid metal flow in a geometry similar to the horizontal Bridgman configuration for crystal growth[J].International Journal of Heat and Mass Transfer,1999,42:4345-4362.
[72]Geiger G H,Pokier D R.Transport Phenomena in Metallurgy[M].AddisonWesley publishing company,1973,85-86
[73]尚晓江,等.ANSYS结构有限元高级分析方法与范例应用[M].北京:中国水利水电出版社,2006
[74]李文彬.磁力应用工程[M].北京:兵器工业出版社,1991
[75]Charles Vives.Crystallization of aluminum alloys in the presence of vertical electromagnetic force fields[J].Journal of Crystal Growth,1997,173:541-549
[76]Griffiths W D,McMartney D G.The effect of electromagnetic stirring during solidification on the structure of Al-Si alloys[J].Materials Science and Engineering,1996,A216:47-60
[77]王学东,时海芳,张伟强,等.电磁搅拌Al-Si合金宏观组织细化机理[J].辽宁工程技术大学学报,2000,19(4):430-432
[78]周永欣,谢辉,吕振林.电磁搅拌对铝硅合金显微组织的影响[J].铸造技术,2003,24(3):199-201
[79]坚增运,常芳娥,马卫宏.金属熔体的形核和过冷度[J].中国科学[E]:2000,30(1):9-12
[80]刘国勋.金属学原理[M].北京:冶金工业出版社,1980
[81]胡汉起.金属凝固原理[M].北京:机械工业出版社,2000
[82]Jung B I,Jung C H,Hart T K,et al.Electromagnetic stirring and Sr modification in A356alloy[J].Journal of Materials Processing Technology,2001,111:69-73
[83]黄明志,石德珂,金志浩.金属力学性能[M].西安:西安交通大学出版社,1986
[84]哈富宽.金属力学性质的微观理论[M].北京:科学出版社
[85]周尧和,胡状麒,介万奇.凝固技术[M].北京:机械工业出版社,1998
[86]Dahle A K,Lee Y C,Mark D N.Development of the as-cast microstructure in magnesium-aluminium alloys[J].J Light Metals,2001,(1):61-72
[87]Guangling Song,Andrej Atrens,Matthew Dargusch.Influence of Microstructure on the corrosion of Die Cast AZ91D[J].Corrosion Science,1999,(41):249-273
[88]Liu X,Xiang Y,Wang Q,Ding W.Corrosion control technologies for magnesium alloys[J].Corrosion Science and Protection Technology,2001,13(4):211-223