合金元素Mo对Laves相TaCr_2合金显微组织及断裂韧性的影响
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摘要
采用机械合金化+热压烧结的工艺路线制备Laves相TaCr_2合金,研究合金元素Mo对其显微组织、力学性能,特别是韧化效果的影响。结果表明:当Mo含量由0增加到5%(摩尔分数)时,Mo取代Laves相TaCr_2中Cr的位置为主。当Mo含量增加到7.6%和10%时,Mo取代Ta的位置更占优势。添加合金元素Mo的Laves相TaCr_2合金较未合金化的TaCr_2硬度略有降低;当Mo添加量≤7.6%,合金的断裂韧性微弱下降,当Mo含量达到10%时,合金断裂韧性要高于Mo添加量小于7.6%时的TaCr_2合金,达到4.26 MPa·m1/2。
Laves phase TaCr_2 alloys were prepared by mechanical alloying and hot-pressing sintering process,and the influences of alloy element Mo addition on microstructure,mechanical properties,especially fracture toughness of the TaCr_2 alloys were studied. The results show that Mo preferentially substitutes the Cr sites in the Laves phase TaCr_2 with the increasing of the Mo content from 0 to 5%( mole fraction). When the Mo content is 7. 6%-10%,Mo prefers to occupy the Ta sites. The hardness of the Laves phase TaCr_2 alloy with the addition of the alloying element Mo is slightly lower than that of the pristine TaCr_2 alloy. The fracture toughness of the alloy decreases slightly when the Mo content is less than 7. 6%,and becomes 4. 26 MPa·m1/2 when the Mo content is 10%.
Laves phase TaCr_2 alloys were prepared by mechanical alloying and hot-pressing sintering process,and the influences of alloy element Mo addition on microstructure,mechanical properties,especially fracture toughness of the TaCr_2 alloys were studied. The results show that Mo preferentially substitutes the Cr sites in the Laves phase TaCr_2 with the increasing of the Mo content from 0 to 5%( mole fraction). When the Mo content is 7. 6%-10%,Mo prefers to occupy the Ta sites. The hardness of the Laves phase TaCr_2 alloy with the addition of the alloying element Mo is slightly lower than that of the pristine TaCr_2 alloy. The fracture toughness of the alloy decreases slightly when the Mo content is less than 7. 6%,and becomes 4. 26 MPa·m1/2 when the Mo content is 10%.
引文
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[2]Liu C T,Zhu J H,Brand M P,et al.Physical metallurgy and mechanical properties of transition-metal Laves phase alloys[J].Intermetallics,2000,8(9/11):1119-1129.
[3]Brand M P,Zhu J H,Liu C T,et al.Intermetallic reinforced Cr alloys for high-temperature use[J].Materials at High Temperatures,1999,16(4):189-193.
[4]Brand M P,Zhu J H,Liu CT,et al.Oxidation resistance and mechanical properties of Laves phase reinforced Cr in-situ composites[J].Intermetallics,2000,8(9/11):1111-1118.
[5]Ohta T,Nakagawa Y,Kaneno Y,et al.Microstuctures and mechanical properties of Nb Cr2and Zr Cr2Laves phase alloys prepared by powder metallurgy[J].Journal of Materials Science,2003,38(4):657-665.
[6]Brady M P,Liu C T,Zhu J H,et al.Effects of Fe additions on the mechanical properties and oxidation behavior of Cr2Ta Laves phase reinforced Cr[J].Scripta Materialia,2005,52(9):815-819.
[7]Takssugi T.Defect structures and room-temperature mechanical properties of C15 Laves phase in Zr-X-Cr(X:Nb,Ta and Hf)alloy systems[J].Materials Science Forum,2005,502:169-174.
[8]Ohta T,Kaneno Y,Inoue H,et al.Phase field and room-temperature mechanical properties of the C15 Laves phase in the Zr-Ta-Cr alloy system[J].Metallurgical and Materials Transactions A,2005,36(3):583-590.
[9]Fujita M,Kaneno Y,Takasugi T.Phase field and room-temperature mechanical properties of C15 Laves phase in Nb-Hf-Cr and Nb-Ta-Cr alloy systems[J].Journal of Alloys and Compounds,2006,424(1/2):283-288.
[10]Wang D F,Liaw P K,Liu C T,et al.Processing and microstructures of Cr-Ta-Mo composites reinforced by the Cr2Ta Laves phase[C]∥Tennessee:17th Annual Conference on Fossilenergy Materials,2003.
[11]Bhowmik A,Jones C N,Edmonds I M,et al.Effect of Mo,Al and Si on the microstructure and mechanical properties of Cr-Cr2Ta based alloys[J].Journal of Alloys and Compounds,2012,530(2):169-177.
[12]Hazzledine P M,Pirouz P.Synchroshear transformations in laves phases[J].Scripta Metallurgica et Materialia,1993,28(10):1277-1282.
[13]郑海忠,鲁世强,祝建业,等.合金元素Al对Laves相Nb Cr2显微组织及断裂韧性的影响[J].稀有金属材料与工程,2009,38(1):80-85.ZHENG Hai-zhong,LU Shi-qiang,ZHU Jian-ye,et al.Effects of Al on the microstructure and fracture toughness of Nb Cr2Alloys[J].Rare Metal Materials and Engineering,2009,38(1):80-85.
[14]Mayera B,Antona H,Botta E,et al.Ab-initio calculation of the elastic constants and thermal expansion coefficients of Laves phases[J].Intermetallics,2003,11(1):23-32.
[15]Yao Q,Sun J,Zhang Y,et al.First-principles studies of ternary site occupancy in the C15 Nb Cr2Laves phase[J].Acta Materialia,2006,54(13):3585-3591.
[16]Jiang C.Site preference of early transition metal elements in C15 Nb Cr2[J].Acta Materialia,2007,55(5):1599-1605.
[17]Wu B,Liu H L,Huang C R,et al.Prediction of the site ordering behaviours of elements in C15 Nb Cr2-based intermetallics by combining thermodynamic model with ab-initio calculation[J].Intermetallics,2013,35(2):104-109.
[18]Liu C T,Tortorelli P F,Horton J A,et al.Effect of alloy additions on microstructure and properties of Cr-Cr2Nb alloys[J].Materials Science and Engineering,1996,A214(1/2):23-32.
[19]Pearson W B.The Crystal Chemistry and Physics of Metals and Alloys[M].New York:published by John Wiley and Sons Ltd,1972.
[20]李长青,张俊才,董胜敏,等.粉末冶金教程[M].徐州:中国矿业大学出版社,2010.
[21]阮建明,黄培云.粉末冶金原理[M].北京:机械工业出版社,2013.
[22]Davidson D L,Chan K S,Anton D L.The effects on fracture toughness of ductile-phase composition and morphology in Nb-Cr-Ti and Nb-Si in situ composites[J].Metallurgical and Materials Transactions A,1996,27(10):3007-3018.