Mekanik Alaşımlama ile Üretilen Nanokristal Yapılı Östenitik Paslanmaz Çelik Alaşımlarında Y ve nano - Y2O3 İlavelerinin Tane Büyümesi ve Sertliğe Etkisi

Hasan Kotan
207 49

Öz


Bu çalışmada, Fe74Cr18Ni8 paslanmaz çelik alaşımı Y elementi ve nano boyutta Y2O3 ilaveleri ile mekanik alaşımlama yöntemi kullanılarak nanokristal yapıda üretilmiş ve 1100 ºC’ye kadar farklı sıcaklıklarda tavlama işlemine tabii tutulmuştur. X-ışınları kırınımı, geçirimli elektron mikroskobu ve odaklanmış iyon demeti mikroskobu kullanılarak sıcaklığa bağlı olarak mikroyapıda meydana gelen değişimler incelenmiştir. Mikroyapının malzeme sertliğine etkisinden faydalanılarak tavlama sıcaklığına bağlı olarak mekanik özelliklerdeki değişimler tespit edilmiştir. Elde edilen sonuçlar denge durumunda ymk kafes yapısına sahip olan bu paslanmaz çelik kristal yapılarının mekanik alaşımlama sırasındaki yoğun plastik deformasyondan dolayı hmk kafes yapısındaki a’ – martenzite dönüştüğünü göstermektedir. Mekanik alaşımlamadan sonra uygulanan tavlama işlemi ile sıcaklığa bağlı olarak farklı oranlarda martenzit – östenit tersine faz dönüşümünün gerçekleştiği tespit edilmiştir. Nanokristal yapılı Fe74Cr18Ni8 paslanmaz çelik alaşımında yüksek tane sınırı alanından dolayı yüksek sıcaklıklarda meydana gelen ve mikrometre seviyelerine ulaşan tane boyutunun, Y ve Y2O3 ilaveleri ile 1100 °C’de yapılan tavlamadan sonra bile yaklaşık olarak 150 nm seviyesinde tutulduğu ve sertliğinin ise 6,5 GPa seviyelerinde korunduğu tespit edilmiştir.


Anahtar kelimeler


paslanmaz çelikler; tane büyümesi; faz dönüşümü; mekanik alaşımlama; sertlik

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Referanslar


Koch C.C., Structural nanocrystalline materials: an overview, J. Mater. Sci., 42, 1403-1414, 2007.

Suryanarayana C., Recent developments in nanostructured materials, Adv. Eng. Mater., 7, 983-992, 2005.

Gleiter H., Hahn H., Schimmel T., Advances in nanomaterials, B. J. Nanotechnol., 4, 805-806, 2013.

Lo K.H., Shek C.H.,bLai J.K.L., Recent developments in stainless steels, Mater. Sci. Eng. R, 65, 39-104, 2009.

Koch C.C., The Synthesis of Nonequilibrium Structures by Ball-Milling, Mechan. Alloy., 88, 243-261, 1992.

Suryanarayana C., Koch C.C., Nanocrystalline materials - Current research and future directions, Hyperfine Interactions, 130, 5-44, 2000.

Spencer K., Conlon K.T., Brechet Y., Embury J.D., The strain induced martensite transformation in austenitic stainless steels Part 2-Effect of internal stresses on mechanical response, Mater. Sci. Technol., 25, 18-28, 2009.

Spencer K., Veron M., Yu-Zhang K., Embury J.D., The strain induced martensite transformation in austenitic stainless steels Part 1-Influence of temperature and strain history, Mater. Sci. Technol., 25, 7-17, 2009.

Koch C.C., Scattergood R.O., Youssef K.M., Chan E.H., Zhu Y.T., Nanostructured materials by mechanical alloying: new results on property enhancement, J. Mater. Sci., 45, 4725-4732, 2010.

Al-Joubori A.A., Suryanarayana C., Synthesis and stability of the austenite phase in mechanically alloyed Fe-Cr-Ni alloys, Mater. Lett., 187, 140-143, 2017.

Kotan H., Darling K. A., Phase transformation and grain growth behavior of a nanocrystalline 18/8 stainless steel, Mater. Sci. and Eng. A, 686, 168-175, 2017.

Kotan H., Saber M., Koch C.C., Scattergood R.O., Effect of annealing on microstructure, grain growth, and hardness of nanocrystalline Fe-Ni alloys prepared by mechanical alloying, Mater. Sci. and Eng. A, 552, 310-315, 2012.

Malow T.R., Koch C.C., Grain growth of nanocrystalline materials - A review in Synthesis and Processing of Nanocrystalline Powder, 33-44, 1996.

Saber M., Kotan H., Koch C.C., Scattergood R.O., A predictive model for thermodynamic stability of grain size in nanocrystalline ternary alloys, J. Appl. Phys., 114, 2013.

Saber M., Kotan H., Koch C.C., Scattergood R.O., Thermodynamic stabilization of nanocrystalline binary alloys, J. Appl. Phys., 113, 2013.

Kirchheim R., Reducing grain boundary, dislocation line and vacancy formation energies by solute segregation. I. Theoretical background, Acta Mater., 55, 5129-5138, 2007.

Weissmuller J., Alloy Thermodynamics in Nanostructures, J. Mater. Res., 9, 4-7, 1994.

Chookajorn T., Murdoch H.A., Schuh C.A., Design of Stable Nanocrystalline Alloys, Science, 337, 951-954, 2012.

Driver J.H., Stability of nanostructured metals and alloys, Scr. Mater., 51, 819-823, 2004.

Liu F., Rirchheim R., Nano-scale grain growth inhibited by reducing grain boundary energy through solute segregation, J. Cryst. Growth, 264, 385-391, 2004.

Li L.L., Xu W.Z., Saber M., Zhu Y.T., Koch C.C., Scattergood R.O., Influence of scandium addition on the high-temperature grain size stabilization of oxide-dispersion-strengthened (ODS) ferritic alloy, Mater. Sci. and Eng. A, 636, 565-571, 2015.

Darling K.A., Huskins E. L., Schuster B. E., Wei Q., Kecskes L.J., Mechanical properties of a high strength Cu-Ta composite at elevated temperature, Mater. Sci. and Eng. A, 638, 322-328, 2015.

Atwater M.A., Roy D., Darling K.A., Butler B.G., Scattergood R.O., Koch C.C., The thermal stability of nanocrystalline copper cryogenically milled with tungsten, Mater. Sci. and Eng. A, 558, 226-233, 2012.

Saber M., Kotan K., Koch C.C., Scattergood R.O., Thermal stability of nanocrystalline Fe-Cr alloys with Zr additions, Mater. Sci. and Eng. A, 556, 664-670, 2012.

Kotan H., Darling K.A., Saber M., Scattergood R.O., Koch C.C., Thermal stability and mechanical properties of nanocrystalline Fe-Ni-Zr alloys prepared by mechanical alloying, J. Mater. Sci., 48, 8402-8411, 2013.

Darling K.A., Chan R.N., Wong P.Z., Semones J.E., Scattergood R.O., Koch C.C., Grain-size stabilization in nanocrystalline FeZr alloys, Scr. Mater., 59, 530-533, 2008.

Xu W.Z., Li, L.L. Saber M., Koch C.C., Zhu Y.T., Scattergood R.O., Nano ZrO2 particles in nanocrystalline Fe-14Cr-1.5Zr alloy powders, J. Nucl. Mater., 452, 434-439, 2014.

Kotan H., Darling K.A., Scattergood R.O., Koch C.C., Influence of Zr and nano-Y2O3 additions on thermal stability and improved hardness in mechanically alloyed Fe base ferritic alloys, J. Alloys. Compd., 615, 1013-1018, 2014.

Langford J.I., Scherrer after sixty years: a survey and some new results in the determination of crystalline size, J. Appl. Crystallogr., 11, 102-113, 1978.

Spencer K., Embury J.D., Conlon K.T., Veron M., Brechet Y., Strengthening via the formation of strain-induced martensite in stainless steels, Mater. Sci. and Eng. A, 387, 873-881, 2004.

Nagy E., Mertinger V., Tranta F., Solyom J., Deformation induced martensitic transformation in stainless steels, Mater. Sci. and Eng. A, 378, 308-313, 2004.

Delogu F., A few details of the austenite to martensite phase transformation in 304 stainless steel powders under mechanical processing, Acta Mater., 59, 2069-2074, 2011.

Das A., Sivaprasad S., Ghosh M., Chakraborti P.C., Tarafder S., Morphologies and characteristics of deformation induced martensite during tensile deformation of 304 LN stainless steel, Mater. Sci. and Eng. A, 486, 283-286, 2008.

Lee S.J., Park Y.M., Lee Y.K., Reverse transformation mechanism of martensite to austenite in a metastable austenitic alloy, Mater. Sci. and Eng. A, 515, 32-37, 2009.

Leem D.S., Lee Y.D., Jun J.H., Choi C.S., Amount of retained austenite at room temperature after reverse transformation of martensite to austenite in an Fe-13%Cr-7%Ni-3%Si martensitic stainless steel, Scr. Mater., 45, 767-772, 2001.

Brofman P.J. Ansell G.S., On the Effect of Fine-Grain Size on the Ms Temperature in Fe-27ni-0.025c Alloys, Metall. Mater. Trans. A., 14, 1929-1931, 1983.

Tomimura K., Takaki S., Tokunaga Y., Reversion Mechanism from Deformation Induced Martensite to Austenite in Metastable Austenitic Stainless-Steels, ISIJ Int., 31, 1431-1437, 1991.

Liu F., Kirchheim R., Grain boundary saturation and grain growth, Scr. Mater., 51, 521-525, 2004.

Cahn J.W., The impurity-drag effect in grain boundary motion, Acta Metall., 10, 789-798, 1962.

Humphreys F.J., Hatherly M., Recrystallization and related annealing phenomena. Oxford, UK, Elsevier, 2004.

Guduru R.K., Scattergood R.O., Koch C.C., Murty K.L., Guruswamy S., McCarter M.K., Mechanical properties of nanocrystalline Fe-Pb and Fe-Al2O3, Scr. Mater., 54, 1879-1883, 2006.

Bacon D.J., Kocks U.F., Scattergood R.O., "The effect of dislocation self-interaction on the Orowan stress," Philos. Mag., 28, 1241-1263, 1973.




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