Gd对Al-5Mg-2Si-Mn合金组织与力学性能的影响
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摘要
研究了Gd对Al-5Mg-2Si-Mn合金铸态组织、相结构、力学性能和断口形貌的影响。研究发现,Gd对Al-5Mg-2SiMn合金中的初生α-Al及共晶Mg_2Si相具有很强的变质和细化作用,当Gd含量为0.4%时,变质和细化效果最为明显,二次枝晶间距由未变质处理的28.23μm减小到12.96μm,共晶Mg_2Si尺寸从9.38μm减少到5.07μm。且合金的力学性能显著提高,抗拉强度、伸长率和硬度(HRB)分别由未细化变质的235MPa、3.9%和33.21增加至328MPa、6.0%和43.33,合金的断裂方式由脆性断裂转变为韧性断裂。
Effects of Gd on the microstructure,phase structure,mechanical properties and fracture morphology of Al-5Mg-2Si-Mn alloy were analyzed.The results reveal that the Gd element presents a strong modification and refinement effect on the primaryα-Al phase and eutectic Mg_2Si phase,and the effect of modification and refinement is desirable when Gd content is 0.4%.The distance between secondary dendrites are decreased from 28.23μm un-modified ones to 12.96μm,and eutectic Mg_2Si size is decreased from 9.38μm to 5.07μm.The tensile strength,elongation and hardness of the alloy treated by 0.4% Gd are increased from 235MPa,3.9%and 33.21HRB to 328MPa,6.0% and 43.33HRB,respectively,and the fracture mode is changed from brittleness to dimple structure.
Effects of Gd on the microstructure,phase structure,mechanical properties and fracture morphology of Al-5Mg-2Si-Mn alloy were analyzed.The results reveal that the Gd element presents a strong modification and refinement effect on the primaryα-Al phase and eutectic Mg_2Si phase,and the effect of modification and refinement is desirable when Gd content is 0.4%.The distance between secondary dendrites are decreased from 28.23μm un-modified ones to 12.96μm,and eutectic Mg_2Si size is decreased from 9.38μm to 5.07μm.The tensile strength,elongation and hardness of the alloy treated by 0.4% Gd are increased from 235MPa,3.9%and 33.21HRB to 328MPa,6.0% and 43.33HRB,respectively,and the fracture mode is changed from brittleness to dimple structure.
引文
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[2]JI S,WATSON D,FAN Z,et al.Development of a super ductile diecast Al-Mg-Si alloy[J].Mater.Sci.Eng.,2012,A556(9):824-833.
[3]胡祖麒,万里,吴晗,等.高强韧压铸Al-Mg-Si-Mn合金的微观组织及力学性能[J].中国有色金属学报,2013,23(3):616-622.
[4]QIN Q D,ZHAO Y G,ZHOU W,et al.Effect of phosphorus on microstructure and growth manner of primary Mg2Si crystal in Mg2Si/Al composite[J].Mater.Sci.Eng.,2007,A447(1-2):186-191.
[5]QIN Q D,ZHAO Y G,CONG P J.Strontium modification and formation of cubic primary Mg2Si crystals in Mg2Si/Al composite[J].J.Alloy Compd.,2008,454(1-2):142-146.
[6]HADIAN R,EMAMY M,VARAHRAM N,et al.The effect of Li on the tensile properties of cast Al-Mg2Si metal matrix composite[J].Mater.Sci.Eng.,2008,A490(1-2):250-257.
[7]EMAMY M,KHORSHIDI R,HONARBAKHSH R A.The influence of pure Na on the microstructure and tensile properties of AlMg2Si metal matrix composite[J].Mater.Sci.Eng.,2011,A528(13-14):4 337-4 342.
[8]FARAHANY S,GHANDVAR H,NORDIN N A,et al.Effect of primary and eutectic Mg2Si crystal modifications on the mechanical properties and sliding wear behaviour of an Al-20Mg2Si-2Cu-xBi composite[J].J.Mater.Sci.Technol.,2016,32(11):1 083-1 097.
[9]SHI Z M,WANG Q,SHI Y T,et al.Microstructure and mechanical properties of Gd-modified A356aluminum alloys[J].J.Rare Earths,2015,33(9):1 004-1 009.
[10]刘政,谌庆春.Gd对半固态A356合金初生α相的细化机制[J].特种铸造及有色合金,2013,33(9):793-796.
[11]YE L Y,HU J L,TANG C P,et al.Modification of Mg2Si in Mg-Si alloys with gadolinium[J].Mater.Characterization,2013,79(1-2):1-6.
[12]孙伟成,张淑荣,侯爱芹.稀土在铝合金中的行为[M].北京:兵器工业出版社,1992.
[13]PEI Y T.Functionally graded materials produced by laser:cladding[J].Acta Mater.,2001,49(7):2 617-2 624.
[14]王孝良,周崎,王喆.Nd对原位自生Mg2Si/Al复合材料的变质作用[J].热加工工艺,2013,42(8):115-120.
[15]陈继飞,杨军军.稀土La对Al-Si合金的变质作用机理研究[J].铸造技术,2008,29(5):658-661.
[16]司颐,王喆,武晓峰.Bi对过共晶Al-15Mg2Si合金Mg2Si相的变质作用[J].铸造技术,2013,34(3):259-262.