Mekanik Olarak Sentezlenen NiTi + Zn Tozlarının Karakterizasyonu ve Sinterlenelebilirliğinin Araştırılması

Bu çalışmada; önalaşımlı NiTi tozları ve % 2, % 4, % 6, % 8 ve % 10 Zn toz oranları kullanılarak bilyeli değirmende 60 dakika mekanik öğütme işlemine tabi tutulmuştur. Öğütülen NiTi + Zn toz karışımları 750 MPa basınç altında presleme sonrası 1000°C’de 60 dakika sinterlenmiştir. Öğütülen ve presleme sonrası sinterlenen numunelere mikroyapısal değişiklikleri tespit etmek için; Taramalı Elektron Mikroskobu (SEM), Element Dağılım Spektrometresi (EDS), Diferansiyel Taramalı Kalorimetre (DSC) ve X-Ray (XRD) analizleri uygulanmıştır. NiTi + Zn toz karışımlarında artan Zn oranına bağlı olarak, toz morfolojisinde değişiklikler tespit edilmiş ve özellikle % 10 Zn ilave edilen tozlarda öğütme sonrası NiTi tozlarının yüzeyini homojen bir şekilde tamamen kapladığı tespit edilmiştir. NiTi + Zn tozlarının 1000°C’de 60 dakika sinterleme sonrası Zn’nin sıvı faz sinterlenmesi ile yapıda NiTi tozlarının arasında bir bağ oluşmuş ve böylece düşük sıcaklıklarda sinterlenme işlemi gerçekleştirilebilmiştir. Ayrıca; NiTi + % 10Zn içeriği ile homojen ve pürüzsüz bir mikro yapı elde edilmiştir.

Anahtar Kelimeler:

Önalaşımlı NiTi tozları, ŞBA, toz metalurjisi

Investigation of Characterization and Sinterability of Mechanically Synthesized NiTi + Zn Powders

In this study; prealloyed NiTi powders and ball mills with 2%, 4%, 6%, 8% and 10% Zn powder ratios were subjected to mechanical milling for 60 minutes. The milled NiTi + Zn powder mixtures were pressed under 750 MPa pressurize and then sintered at 1000°C for 60 minutes. In order to determine the microstructural changes in the samples which were milled, pressed and then sintered samples; SEM, EDS, DSC and XRD analyses were applied, respectively. Changes in powder morphology were observed, depending of the increasing Zn content in the NiTi + Zn powder mixtures and it was determined that the powders containing 10% Zn completely covered the surface of the NiTi powders in a homogeneous manner after milling. Zn content in the micro structure also provided the alloy to be sintered at low temperatures by completely filling the gaps and pores after the sintering process at 1000°C for 60 min. In addition, a homogenous and smooth microstructure was obtained with NiTi + 10Zn% content.

Keywords:

Prealloyed NiTi powders, SMA, powder metallurgy,

PDF

___

[1] Cengiz E., Ozkendir O.M., Kaya M., Tirasoglu E., Karahan I.H., Kimura S., Hajiri T., “Alloying effect on K-shell fluorescence parameters of porous NiTi shape memory alloys”, Journal of Electron Spectroscopy and Related Phenomena, 192: 55–60, (2014).
[2] Ota A., Yazaki Y., Yokoyama K. and Sakai J., “Hydrogen Absorption and Thermal Desorption Behavior of Ni-Ti Superelastic Alloy Immersed in Neutral NaCl and NaF Solutions under Applied Potential”, Materials Transactions, 50, 7 : 1843 - 1849, (2009).
[3] Tosun G., Ozler L., Kaya M., Orhan N., “A study on microstructure and porosity of NiTi alloy implants produced by SHS”, Journal of Alloys and Compounds, 487 : 605–611, (2009).
[4] Elahinia M.H., Hashemi M., Tabesh M., Bhaduri S.B., “Manufacturing and processing of NiTi Implants; Prog. Mater Sci. 57 : 911–946, (2012).
[5] Thier M., Hühner M., Kobus E., Drescher D., Bourauel C., “Microstructure of As-cast NiTi alloy”, Materials Characterization, 27 :3, 133-140, (1991).
[6] Ogawa T., Yokoyama K., Asaoka K. and Sakai J., “Hydrogen Embrittlement of Ni–Ti Superelastic Alloy in Ethanol Solution Containing Hydrochloric Acid”, : Mater. Sci. Eng. A, 393 : 239–246, (2005).
[7] Yokoyama K., Ogawa T., Asaoka K., Sakai J. and Nagumo M., “Degradation of Tensile Strength of Ni–Ti Superelastic Alloy due to Hydrogen Absorption in Methanol Solution Containing Hydrochloric Acid” : Mater. Sci. Eng. A, 360 : 153–159, (2003).
[8] Aksöz S., “Microstructural and Mechanical Investigation of NiTi Intermetallics Produced by Hot Deformation Technique”, Arab J Sci Eng, 42: 2573, (2017).
[9] Aksöz S., Bostan B., “Characteric Properties of NiTi Shape memory Alloy Powders with Powder Injection Molding” International Multidisciplinary Microscopy Congress. Springer Proceedings in Physics Switzerland, 18: 129-142, (2014).
[10] Krone L., Schüller E., Bram M., Hamed O., Buchkremer H.P., Stöver D., “Mechanical Behaviour of NiTi Parts Prepared by Powder Metallurgical Methods”, Materials Science and Engineering A, 378 : 185–190, (2004).
[11] Shearwood C., Fu Y.Q., Yu L., Khor K.A., “Spark Plasma Sintering of TiNi Nano Powder”, Scripta Materialia, 52: 455–460, (2006).
[12] Biswas A., ““Porous NiTi by Thermal Explosion mode of SHS: Processing, Mechanism and Generation of Single Phase Microstructure”, Acta Materialia, 53 : 1415–1425, (2005).
[13] Aksöz S., Özdemir A.T, Bostan B., “Alloyed AA2014 Aluminium Powders Synthesised With Carbon and Determined Properties” J. Fac. Eng. Arch. Gazi Univ., Vol 27., No 1, 109-115, (2012).
[14] Aksöz S., Demir Ü., Ada H., Gökmeşe H., Bostan B., “NiTi Şekil Bellekli Alaşım Tozlarına Mekanik Alaşımlama Yöntemi Kullanılarak Elementel Ni ve Ti Tozlarının İlavesinin Mikroyapısal İncelenmesi”, GU J Sci, Part C, 5 (1): 99-106, (2017).
[15] Mousavi T., Karimzadeh F., Abbasi M.H., “Synthesis and characterization of nanocrystalline NiTi intermetallic by mechanical alloying”, Mater. Sci. Eng. A, 487 : 46 – 51, (2008).
[16] Jiang X., Liu Q., Zhang L., “Electrochemical hydrogen storage property of NiTi alloys with different Ti content prepared by mechanical alloying”, Rare Met. 30 63 – 67, (2011).
[17] Takasaki A., “Mechanical alloying of the Ti-Ni system”, Phys. Stat. Sol. 169A, 183 – 191, (1998).
[18] Karolus M., Panek J., “Nanostructured Ni-Ti alloys obtained by mechanical synthesis and heat treatment”, Journal of Alloys and Compounds, 658 : 709 – 715, (2016).
[19] German R.M., “Sintering Science and Technology”, R.M. German, G.L. Messing and R.G. Cornwall (eds.), Materials Research Laboratory, The Pennsylvania State University, University Park, PA, pp:259-264, (2000).
[20] German R.M: “Sintering Theory and Practice”, ISBN: 978-0-471-05786-4, 1-568, 21st edition, April, Wiley-Interscience, (2008).
[21] Suryanarayana C., “Mechanical alloying and milling”, Prog. Mater. Sci., 46 1–184, (2001).
[22] Nishida M., Hara T., Ohba T., Yamaguchi K., Tanaka K., and Yamauchi K., “Experimental Consideration of Multistage Martensitic Transformation and Precipitation Behavior in Aged Ni-Rich Ti-Ni Shape Memory Alloys”, Materials Transactions, 44(12) : 2631-2636, (2003).
[23] Karabulut, H., Çıtak, R., Çinici, H., “Effect Of Mechanical Alloying Duration On Transverse Rupture Strength of Al+10% Al2O3 Composites, J. Fac. Eng. Arch. Gazi Univ., 28(3): 635-643, (2013).
[24] Özer A., Tür Y.K., “Tetragonal Zirkonya Katkılı Cr3C2-NiCr Sermet Kompozitlerin Karakterizasyonu ve Mekanik Özellikleri”, AKU J. Sci. Eng., 14 : OZ5760, (375-380), (2014).
[25] Liu B., Huang S.,, Humbeeck J.V., Vleugels J., “Rapid synthesis of dense NiTi alloy through spark plasma sintering of a TiH2/Ni powder mixture”, Materials Letters, 191 : 89–92, (2017).
[26] Li. D.S., Zhang Y.P., Eggeler G., Zhang X.P., “High porosity and high-strength porous NiTi shape memory alloys with controllable pore characteristics”, Journal of Alloys and Compounds, 470, L1–L5, (2009).
[27] Zhang L., He Z.Y., Tan J., Zhang Y.Q., Stoica M., Prashanth K.G., Cordill M.J., Jiang Y.H., Zhou R., Eckert J., “Rapid fabrication of function-structure-integrated NiTi alloys: Towards a combination of excellent superelasticity and favorable bioactivity”, Intermetallics, 82: 1-13, (2017).
[28] Wang L., Wang C., Lu W., Zhang D., “Superelasticity of NiTi–Nb metallurgical bonding via nanoindentation observation”, Materials Letters, 161: 255–258, (2015).