铸造WE43镁合金低温至高温准静态拉伸力学行为的研究
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摘要
采用光学显微镜、扫描和透射电子显微镜对铸造WE43镁合金在-196～300℃准静态拉伸力学行为及断裂行为进行研究.结果表明:标准热处理态(T6)WE43镁合金组织具有等轴晶粒,平均晶粒尺寸约104μm,晶内主要由细小弥散分布的β′和β_1相组成,晶界具有较粗大的第二相,并且在晶界附近形成约300 nm宽度的无析出相区域;变形温度降低至-196℃时,合金的断裂延伸率仍具有3.2%,表明合金不存在完全的低温脆性断裂,原因可能是晶界附近存在的无析出相区域可以协调一定量的塑性变形;当变形温度从室温升高至250℃时,合金的断裂延伸率从2.4%显著增加至13.5%,表明合金发生韧脆转变现象,原因可能是合金在250℃变形时非基面滑移的大量启动和晶界滑动能力的大幅增加.
The quasi-static tensile mechanical behavior including fracture behavior of cast WE43 magnesium alloy at-196～300 ℃was investigated by OM, SEM and TEM. The results indicate that the standard heat treated(T6) alloy has equiaxed grains with average grain size of 104 μm. The crystals are mianly composed of finely dispersed β′ and β_(1 )precipitates within the matrix and coarse particles at grain boundaries with precipitate free zones of width about 300 nm. When the deformation temperature is decreased to-196 ℃, the alloy still achieves a certain fracture elongation of 3.2%, rather than a complete brittle fracture. The cause is partly attributed to that the precipitate free zone could undertake some plastic deformation. When the deformation temperature was increased from 24 ℃ to 250 ℃, the fracture elongation of the alloy is significantly increased from 2.4% to 13.5%, which indicates a brittle-tough transition. This could be due to the increase of non-basal slip and grain boundary slide.
The quasi-static tensile mechanical behavior including fracture behavior of cast WE43 magnesium alloy at-196～300 ℃was investigated by OM, SEM and TEM. The results indicate that the standard heat treated(T6) alloy has equiaxed grains with average grain size of 104 μm. The crystals are mianly composed of finely dispersed β′ and β_(1 )precipitates within the matrix and coarse particles at grain boundaries with precipitate free zones of width about 300 nm. When the deformation temperature is decreased to-196 ℃, the alloy still achieves a certain fracture elongation of 3.2%, rather than a complete brittle fracture. The cause is partly attributed to that the precipitate free zone could undertake some plastic deformation. When the deformation temperature was increased from 24 ℃ to 250 ℃, the fracture elongation of the alloy is significantly increased from 2.4% to 13.5%, which indicates a brittle-tough transition. This could be due to the increase of non-basal slip and grain boundary slide.
引文
[1] 陈振华,陈吉华,全亚杰,等.镁合金[M].北京:化学工业出版社,2004:1-2.
[2] 陈振华.耐热镁合金[M].北京:北京工业出版社,2007:1-4.
[3] LUO A A.Magnesium casting technology for structural applications[J].Journal of Magnesium and Alloys,2013,1(1):2-22.
[4] KING J F.Development of practical high temperature magnesium casting alloys,in:KAINER K U.Magnes Alloy Their Appl.Wiley-VCH,2000:14-22.
[5] MABCHI M,CHINO Y,IWASAKI H.Tensile properties at room temperature to 823 K of Mg-4Y-3RE alloy[J].Materials Transactions-JIM,2002,43(8):2063-2068.
[6] WESSEL E.Abrupt yielding and the ductile-to-brittle transition in body-centered-cubic metals[J].JOM,1957,9(7):930-935.
[7] TANAKA M,TARLETON E,ROBERTS S.The brittle-ductile transition in single-crystal iron[J].Acta Materialia,2008,56(18):5123-5129.
[8] WILSON D.Ductility of polycrystalline magnesium below 300 K[J].J Inst Metals,1970,98:133-143.
[9] KULA A,NOBLE K,MISHRA R,et al.Plasticity of Mg-Gd alloys between 4K and 298K[J].Philosophical Magazine,2016,96(2):134-165.
[10] KANG Y H,YAN H,CHEN R S.Effects of heat treatment on the precipitates and mechanical properties of sand-cast Mg-4Y-2.3Nd-1Gd-0.6Zr magnesium alloy[J].Materials Science and Engineering A,2015,645:361-368.
[11] SOLOMON E.Precipitation behavior of magnesium alloys containing neodymium and yttrium[D].Ann Arbor:University of Michigan,2017.
[12] MABUCHI M,CHINO Y,IWASAKI H.Tensile properties at room temperature to 823 K of Mg-4Y-3RE alloy[J].Materials Transactions,2002,43(8):2063-2068.
[13] SAUNDERS W,STRIETER F.Alloying zirconium to magnesium[J].Transactions of the American foundrymen’s society,1952,60:581-594.
[14] LI J,CHEN R S,MA Y Q,et al.Effect of Zr modification on solidification behavior and mechanical properties of Mg-Y-RE (WE54) alloy[J].Journal of Magnesium and Alloys,2013,1(4):346-351.
[15] NIE J,MUDDLE B.Precipitation in magnesium alloy WE54 during isothermal ageing at 250 C[J].Scripta Materialia,1999,40(10):1089-1094.
[16] NIE J,MUDDLE B.Characterisation of strengthening precipitate phases in a Mg-Y-Nd alloy[J].Acta materialia,2000,48(8):1691-1703.
[17] ANTION C,DONNSDIEU P,PERRARD F,DESCHAMPS A,TASSIN C,PISCH A.Hardening precipitation in a Mg-4Y-3RE alloy[J].Acta materialia,2003,51(18):5335-5348
[18] ANTION C,DONNSDIEU P,PERRARD F,et al.Early stages of precipitation and microstructure control in Mg-rare earth alloys[J].Philosophical Magazine,2006,86(19):2797-2810.
[19] FISHER J C,HART EW,PRY R H.Theory of slip-band formation[J].Physical review,1952,87(6):958.
[20] LOW J,TURKATO A.Slip band structure and dislocation multiplication in silicon-iron crystals[J].Acta metallurgica,1962,10(3):215-227.
[21] HUNSCHE A,NEUMANN P.Quantitative measurement of persistent slip band profiles and crack initiation[J].Acta metallurgica,1986,34(2):207-217.
[22] GUO Y,BRITTON T,WILKINSON A.Slip band-grain boundary interactions in commercial-purity titanium[J].Acta Materialia,2014,76(1):1-12
[23] SANDL?BES S,FRIáKM,NEUGEBAUER J,et al.Basal and non-basal dislocation slip in Mg-Y[J].Materials Science and Engineering:A,2013,576(1):61-68.
[24] WANG F,DONG J,FENG M,et al.A study of fatigue damage development in extruded Mg-Gd-Y magnesium alloy[J].Materials Science and Engineering:A,2014,589(1):209-216.
[25] LIUG,XIN R,SHU X,et al.The mechanism of twinning activation and variant selection in magnesium alloys dominated by slip deformation[J].Journal of Alloys and Compounds,2016,687(5):352-359.
[2] 陈振华.耐热镁合金[M].北京:北京工业出版社,2007:1-4.
[3] LUO A A.Magnesium casting technology for structural applications[J].Journal of Magnesium and Alloys,2013,1(1):2-22.
[4] KING J F.Development of practical high temperature magnesium casting alloys,in:KAINER K U.Magnes Alloy Their Appl.Wiley-VCH,2000:14-22.
[5] MABCHI M,CHINO Y,IWASAKI H.Tensile properties at room temperature to 823 K of Mg-4Y-3RE alloy[J].Materials Transactions-JIM,2002,43(8):2063-2068.
[6] WESSEL E.Abrupt yielding and the ductile-to-brittle transition in body-centered-cubic metals[J].JOM,1957,9(7):930-935.
[7] TANAKA M,TARLETON E,ROBERTS S.The brittle-ductile transition in single-crystal iron[J].Acta Materialia,2008,56(18):5123-5129.
[8] WILSON D.Ductility of polycrystalline magnesium below 300 K[J].J Inst Metals,1970,98:133-143.
[9] KULA A,NOBLE K,MISHRA R,et al.Plasticity of Mg-Gd alloys between 4K and 298K[J].Philosophical Magazine,2016,96(2):134-165.
[10] KANG Y H,YAN H,CHEN R S.Effects of heat treatment on the precipitates and mechanical properties of sand-cast Mg-4Y-2.3Nd-1Gd-0.6Zr magnesium alloy[J].Materials Science and Engineering A,2015,645:361-368.
[11] SOLOMON E.Precipitation behavior of magnesium alloys containing neodymium and yttrium[D].Ann Arbor:University of Michigan,2017.
[12] MABUCHI M,CHINO Y,IWASAKI H.Tensile properties at room temperature to 823 K of Mg-4Y-3RE alloy[J].Materials Transactions,2002,43(8):2063-2068.
[13] SAUNDERS W,STRIETER F.Alloying zirconium to magnesium[J].Transactions of the American foundrymen’s society,1952,60:581-594.
[14] LI J,CHEN R S,MA Y Q,et al.Effect of Zr modification on solidification behavior and mechanical properties of Mg-Y-RE (WE54) alloy[J].Journal of Magnesium and Alloys,2013,1(4):346-351.
[15] NIE J,MUDDLE B.Precipitation in magnesium alloy WE54 during isothermal ageing at 250 C[J].Scripta Materialia,1999,40(10):1089-1094.
[16] NIE J,MUDDLE B.Characterisation of strengthening precipitate phases in a Mg-Y-Nd alloy[J].Acta materialia,2000,48(8):1691-1703.
[17] ANTION C,DONNSDIEU P,PERRARD F,DESCHAMPS A,TASSIN C,PISCH A.Hardening precipitation in a Mg-4Y-3RE alloy[J].Acta materialia,2003,51(18):5335-5348
[18] ANTION C,DONNSDIEU P,PERRARD F,et al.Early stages of precipitation and microstructure control in Mg-rare earth alloys[J].Philosophical Magazine,2006,86(19):2797-2810.
[19] FISHER J C,HART EW,PRY R H.Theory of slip-band formation[J].Physical review,1952,87(6):958.
[20] LOW J,TURKATO A.Slip band structure and dislocation multiplication in silicon-iron crystals[J].Acta metallurgica,1962,10(3):215-227.
[21] HUNSCHE A,NEUMANN P.Quantitative measurement of persistent slip band profiles and crack initiation[J].Acta metallurgica,1986,34(2):207-217.
[22] GUO Y,BRITTON T,WILKINSON A.Slip band-grain boundary interactions in commercial-purity titanium[J].Acta Materialia,2014,76(1):1-12
[23] SANDL?BES S,FRIáKM,NEUGEBAUER J,et al.Basal and non-basal dislocation slip in Mg-Y[J].Materials Science and Engineering:A,2013,576(1):61-68.
[24] WANG F,DONG J,FENG M,et al.A study of fatigue damage development in extruded Mg-Gd-Y magnesium alloy[J].Materials Science and Engineering:A,2014,589(1):209-216.
[25] LIUG,XIN R,SHU X,et al.The mechanism of twinning activation and variant selection in magnesium alloys dominated by slip deformation[J].Journal of Alloys and Compounds,2016,687(5):352-359.