氩气雾化Ti-48Al合金液滴的快速冷却和凝固组织
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摘要
为研究氩气雾化过程中Ti-48Al(原子分数/%)合金液滴的形核和晶粒生长形式,分析液滴冷却过程的温度变化。采用扫描电子显微镜、透射电子显微镜和电子背散射衍射观察粉末的组织形貌,并基于观察建立了初始形核数量、固/液界面速率、冷却速率和液滴直径之间的牛顿冷却模型。结果表明:随着粉末尺寸的增加,初始形核数量呈指数增加,晶核生长时固/液界面从双曲面形式转变为同心圆形式;利用模型数值计算发现,雾化液滴纯液相急剧冷却,冷却速率约为105～106 K·s-1。液滴进入再辉阶段后,温度快速上升后平缓下降,固相冷却阶段冷却速率约为105 K·s-1。
An analytical approach was developed to investigate nucleation and growth of Ti-48 Al(atom fraction/%)alloy droplets during their flight in an argon atomization process.Evolution of microstructure of the solidified powders was investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and electron back-scatter diffraction(EBSD).Newton cooling model based on the initial number of nuclei,liquid/solid interface velocity,cooling rate and size of droplets was established.The results show that statistical nucleation events increase exponentially with the increase of powders size,and the growth of nuclei is transformed from a twinned spherical segment into a concentric liquid/solid interface geometry.Temperature of atomized droplets decreases rapidly with the cooling rate of 105-106 K·s-1.Then temperature increases sharply to near the liquidus temperature during recalescence.When the recalescence is completed,the droplet solidifies at a relatively slower rate.Afterwards the cooling rate of the fully solid phase decreases to about 105 K·s-1.
An analytical approach was developed to investigate nucleation and growth of Ti-48 Al(atom fraction/%)alloy droplets during their flight in an argon atomization process.Evolution of microstructure of the solidified powders was investigated by scanning electron microscopy(SEM),transmission electron microscopy(TEM)and electron back-scatter diffraction(EBSD).Newton cooling model based on the initial number of nuclei,liquid/solid interface velocity,cooling rate and size of droplets was established.The results show that statistical nucleation events increase exponentially with the increase of powders size,and the growth of nuclei is transformed from a twinned spherical segment into a concentric liquid/solid interface geometry.Temperature of atomized droplets decreases rapidly with the cooling rate of 105-106 K·s-1.Then temperature increases sharply to near the liquidus temperature during recalescence.When the recalescence is completed,the droplet solidifies at a relatively slower rate.Afterwards the cooling rate of the fully solid phase decreases to about 105 K·s-1.
引文
[1] KIM Y W.Strength and ductility in TiAl alloys[J].Intermetallics,1998,6(7/8):623-628.
[2]王艳晶,柳乐,宋玫锦.Y微合金化高铌TiAl基合金微观组织研究[J].材料工程,2015,43(1):66-71.WANG Y J,LIU L,SONG M J.Microstructure of Y micro-alloying TiAl based alloy with high Nb content[J].Journal of Materials Engineering,2015,43(1):66-71.
[3] RAO K P,PRASAD Y,SURESH K.Hot working behavior and processing map of aγ-TiAl alloy synthesized by powder metallurgy[J].Materials&Design,2011,32(10):4874-4881.
[4]马李,何录菊,邵先亦,等.电子束沉积TiAl合金的微观形貌及组织结构稳定性[J].材料工程,2016,44(1):89-95.MA L,HE L J,SHAO X Y,et al.Micro-morphology and microstructure stability of TiAl alloy deposited by electronic beam[J].Journal of Materials Engineering,2016,44(1):89-95.
[5]阚文斌,林均品.增材制造技术制备钛铝合金的研究进展[J].中国材料进展,2015,34(2):111-119.KAN W B,LIN J P.Research progress on fabrication of TiAl alloys fabricated by additive manufacturing[J].Materials China,2015,34(2):111-119.
[6]刘咏,黄伯云,贺跃辉,等.热压反应合成TiAl合金的密度及孔隙分布[J].中南工业大学学报,1998,29(5):446-449.LIU Y,HUANG B Y,HE Y H,et al.Densification and porosity distribution of TiAl based alloy prepared by reactive hot pressing[J].Journal of Central South University,1998,29(5):446-449.
[7] SUN J F,CAO F Y,CUI C C,et al.Dynamic behaviors of gas velocity field during metal atomization[J].Powder Metallurgy Technology,2002,20(2):79-81.
[8] MATHUR P,APELIAN D,LAWLEY A.Analysis of the spray deposition process[J].Acta Metallurgica,1989,37(2):429-433.
[9] GRANT P S,CANTOR B,KATGERMAN L.Modelling of droplet dynamic and thermal histories during spray forming-Ⅰindividual droplet behaviour[J].Acta Metallurgica et Materialia,1993,41(11):3097-3108.
[10] LEVI C G,MEHRABIAN R.Heat flow during rapid solidification of undercooled metal droplets[J].Metallurgical and Materials Transactions A,1982,13(2):221-234.
[11] TRIVEDI R,JIN F,ANDERSON I E.Dynamical evolution of microstructure in finely atomized droplets of Al-Si alloys[J].Acta Materialia,2003,51(2):289-300.
[12] JABBAR H,MONCHOUX J P,THOMAS M,et al.Improvement of the creep properties of TiAl alloys densified by spark plasma sintering[J].Intermetallics,2014,46(1):1-3.
[13] SUN Y,KULKARNI K,SACHDEV A K,et al.Synthesis ofγ-TiAl by reactive spark plasma sintering of cryomilled Ti and Al powder blend:partⅡ:effects of electric field and microstructure on sintering kinetics[J].Metallurgical and Materials Transactions A,2014,45(6):2759-2767.
[14] LEVI C G,MEHRABIAN R.Microstructures of rapidly solidified aluminum alloy submicron powders[J].Metallurgical and Materials Transactions A,1982,13(1):13-23.
[15] AISSA A,ABDELOUAHAB M,NOUREDDINE A,et al.Ranz and Marshall correlations limits on heat flow between a sphere and its surrounding gas at high temperature[J].Thermal Science,2015,19(5):1521-1528.
[16] RANZ W E,MARSHALL W R J.Evaporation from drops:partⅠ[J].Chemical Engineering Progress,1952,48(3):141-146.
[17] LEE E S,AHN S.Solidification progress and heat transfer analysis of gas-atomized alloy droplets during spray forming[J].Acta Metallurgica et Materialia,1994,42(9):3231-3243.
[18] SHUKLA P,MANDAL R K,OJHA S N.Non-equilibrium solidification of undercooled droplets during atomization process[J].Bulletin of Materials Science,2001,24(5):547-554.
[19] MARASLI N,HUNT J D.Solid-liquid surface energies in the Al-CuAl2,Al-NiAl3 and Al-Ti systems[J].Acta Materialia,1996,44(3):1085-1096.
[20] HARDING R A,BROOKS R F,POTTACHER G,et al.Thermo-physical properties of a Ti-44Al-8Nb-1Balloy in the solid and molten conditions[C]∥Gamma Titanium Aluminides 2003.Warrendale,US:The Minerals,Metals&Materials Society,2003:75-82.
[21] LI B,LIANG X,EARTHMAN J C,et al.Two dimensional modeling of momentum and thermal behavior during spray atomization ofγ-TiAl[J].Acta Materialia,1996,44(6):2409-2420.
[22] FRANZEN S F,KARLSSON J.γ-titanium aluminide manufactured by electron beam melting[D].Chalmers,Sweden:Chalmers University of Technology,2010.
[2]王艳晶,柳乐,宋玫锦.Y微合金化高铌TiAl基合金微观组织研究[J].材料工程,2015,43(1):66-71.WANG Y J,LIU L,SONG M J.Microstructure of Y micro-alloying TiAl based alloy with high Nb content[J].Journal of Materials Engineering,2015,43(1):66-71.
[3] RAO K P,PRASAD Y,SURESH K.Hot working behavior and processing map of aγ-TiAl alloy synthesized by powder metallurgy[J].Materials&Design,2011,32(10):4874-4881.
[4]马李,何录菊,邵先亦,等.电子束沉积TiAl合金的微观形貌及组织结构稳定性[J].材料工程,2016,44(1):89-95.MA L,HE L J,SHAO X Y,et al.Micro-morphology and microstructure stability of TiAl alloy deposited by electronic beam[J].Journal of Materials Engineering,2016,44(1):89-95.
[5]阚文斌,林均品.增材制造技术制备钛铝合金的研究进展[J].中国材料进展,2015,34(2):111-119.KAN W B,LIN J P.Research progress on fabrication of TiAl alloys fabricated by additive manufacturing[J].Materials China,2015,34(2):111-119.
[6]刘咏,黄伯云,贺跃辉,等.热压反应合成TiAl合金的密度及孔隙分布[J].中南工业大学学报,1998,29(5):446-449.LIU Y,HUANG B Y,HE Y H,et al.Densification and porosity distribution of TiAl based alloy prepared by reactive hot pressing[J].Journal of Central South University,1998,29(5):446-449.
[7] SUN J F,CAO F Y,CUI C C,et al.Dynamic behaviors of gas velocity field during metal atomization[J].Powder Metallurgy Technology,2002,20(2):79-81.
[8] MATHUR P,APELIAN D,LAWLEY A.Analysis of the spray deposition process[J].Acta Metallurgica,1989,37(2):429-433.
[9] GRANT P S,CANTOR B,KATGERMAN L.Modelling of droplet dynamic and thermal histories during spray forming-Ⅰindividual droplet behaviour[J].Acta Metallurgica et Materialia,1993,41(11):3097-3108.
[10] LEVI C G,MEHRABIAN R.Heat flow during rapid solidification of undercooled metal droplets[J].Metallurgical and Materials Transactions A,1982,13(2):221-234.
[11] TRIVEDI R,JIN F,ANDERSON I E.Dynamical evolution of microstructure in finely atomized droplets of Al-Si alloys[J].Acta Materialia,2003,51(2):289-300.
[12] JABBAR H,MONCHOUX J P,THOMAS M,et al.Improvement of the creep properties of TiAl alloys densified by spark plasma sintering[J].Intermetallics,2014,46(1):1-3.
[13] SUN Y,KULKARNI K,SACHDEV A K,et al.Synthesis ofγ-TiAl by reactive spark plasma sintering of cryomilled Ti and Al powder blend:partⅡ:effects of electric field and microstructure on sintering kinetics[J].Metallurgical and Materials Transactions A,2014,45(6):2759-2767.
[14] LEVI C G,MEHRABIAN R.Microstructures of rapidly solidified aluminum alloy submicron powders[J].Metallurgical and Materials Transactions A,1982,13(1):13-23.
[15] AISSA A,ABDELOUAHAB M,NOUREDDINE A,et al.Ranz and Marshall correlations limits on heat flow between a sphere and its surrounding gas at high temperature[J].Thermal Science,2015,19(5):1521-1528.
[16] RANZ W E,MARSHALL W R J.Evaporation from drops:partⅠ[J].Chemical Engineering Progress,1952,48(3):141-146.
[17] LEE E S,AHN S.Solidification progress and heat transfer analysis of gas-atomized alloy droplets during spray forming[J].Acta Metallurgica et Materialia,1994,42(9):3231-3243.
[18] SHUKLA P,MANDAL R K,OJHA S N.Non-equilibrium solidification of undercooled droplets during atomization process[J].Bulletin of Materials Science,2001,24(5):547-554.
[19] MARASLI N,HUNT J D.Solid-liquid surface energies in the Al-CuAl2,Al-NiAl3 and Al-Ti systems[J].Acta Materialia,1996,44(3):1085-1096.
[20] HARDING R A,BROOKS R F,POTTACHER G,et al.Thermo-physical properties of a Ti-44Al-8Nb-1Balloy in the solid and molten conditions[C]∥Gamma Titanium Aluminides 2003.Warrendale,US:The Minerals,Metals&Materials Society,2003:75-82.
[21] LI B,LIANG X,EARTHMAN J C,et al.Two dimensional modeling of momentum and thermal behavior during spray atomization ofγ-TiAl[J].Acta Materialia,1996,44(6):2409-2420.
[22] FRANZEN S F,KARLSSON J.γ-titanium aluminide manufactured by electron beam melting[D].Chalmers,Sweden:Chalmers University of Technology,2010.