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Acta Metall Sin  2018, Vol. 54 Issue (5): 824-830    DOI: 10.11900/0412.1961.2017.00312
Special Issue for the Solidification of Metallic Materials Current Issue | Archive | Adv Search |
Rapid Solidification of Ti-6Al-4V Alloy Micro-Droplets Under Free Fall Condition
Bin ZHAI, Kai ZHOU, Peng Lü, Haipeng WANG()
Department of Applied Physics, Northwestern Polytechnical University, Xi'an 710072, China
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Abstract  

Especially in the past decades, Ti-6Al-4V alloy has received much attention, not only due to its high melting temperature, good corrosion resistance, low density and high hardness, but also because of the diverse and complicated microstructures formed under different conditions. This makes Ti-6Al-4V a potential candidate in both aerospace industries and fundamental research. It is well known that the solidified microstructures of alloy have a great influence on their mechanical properties. Therefore, it is crucial to investigate the mechanical properties of Ti-6Al-4V solidified under different conditions, in particular in the undercooling conditions. However, it is noted that most research on the solidification of Ti-6Al-4V alloy was carried out under equilibrium condition. With respect to Ti-6Al-4V alloy solidified under substantial undercooling conditions, few studies could be found. Thus, it is interesting to study two points: (1) the feature of the microstructure of Ti-6Al-4V alloy solidified under highly undercooled conditions and large cooling rate, (2) the influence of undercooling and cooling rate on the mechanical property of Ti-6Al-4V alloy. To address these two problems, Ti-6Al-4V alloy was rapidly solidified in a drop tube. The main results are summarized as follows. The microstructure of the Ti-6Al-4V alloy solidified under free fall condition displays "lamellar α+βα dendrites→basket-weave α'+β→ needle-like α'→ needle-like α'+ anomalous β " transformation with decreasing the droplets diameter. And the needle-like α' phase in the original boundaries of equiaxed β grains is transformed into a continuous distribution and anomalous structure of β phase when the droplet size is less than about 400 μm. The microhardness of this alloy ranges from 506 kg/mm2 to 785 kg/mm2 when the droplet diameter decreases from 1420 μm to 88 μm, which is much higher than that of the master alloy. For "lamellar structure of α+β phases", "needle-like α' phase" and "needle-like α' phase+ anomalous β phase", the microhardness increases with the decrease of droplet diameter. But for 'basket-weave' microstructure, the microhardness diminishes with the decrease of droplet diameter.

Key words:  titanium alloy      high undercooling      rapid solidification      microstructure      microhardness     
Received:  25 July 2017     
ZTFLH:  TG113.12  
Fund: Supported by National Natural Science Foundation of China (Nos.51474175, 51522102, 51506182 and 51734008) and Aeronautical Science Foundation (No.2016ZF53060)

Cite this article: 

Bin ZHAI, Kai ZHOU, Peng Lü, Haipeng WANG. Rapid Solidification of Ti-6Al-4V Alloy Micro-Droplets Under Free Fall Condition. Acta Metall Sin, 2018, 54(5): 824-830.

URL: 

https://www.ams.org.cn/EN/10.11900/0412.1961.2017.00312     OR     https://www.ams.org.cn/EN/Y2018/V54/I5/824

Fig.1  XRD pattern (a) and DSC curves (b) of Ti-6Al-4V master alloy (ΔH—solid phase transition enthalpy)
Fig.2  Calculated undercooling (ΔT) (a) and cooling rate (Rc) (b) of Ti-6Al-4V alloy vs droplet diameter (D) in drop tube
Fig.3  Solidification microstructures of Ti-6Al-4V alloy
(The α phase is lighter and the β phase is darker)(a) master alloy (b) D=1330 μm droplets, ΔT=30 K, Rc =2.1×103 K/s
Fig.4  Solidification microstructures of Ti-6Al-4V alloy droplets (The insets in the Figs.4e and f indicate that the droplets are spherical)
(a) D=790 μm, ΔT=65 K, Rc=5.0×103 K/s (b) D=700 μm, ΔT=94 K, Rc=5.7×103 K/s
(c) D=600 μm, ΔT=110 K, Rc=9.3×103 K/s (d) D=515 μm, ΔT=124 K, Rc=9.0×103 K/s
(e) D=330 μm, ΔT=174 K, Rc=2.4×104 K/s (f) D=88 μm, ΔT=424 K, Rc=3.9×105 K/s
Fig.5  The volume fraction of β phase of Ti-6Al-4V alloy vs droplet diameter
Fig.6  Microhardness of Ti-6Al-4V alloy vs droplet diameter (Insets show microstructures of Ti-6Al-4V alloy with different diameters)
[1] Devaraj A, Joshi V V, Srivastava A, et al.A low-cost hierarchical nanostructured beta-titanium alloy with high strength[J]. Nat. Commun., 2016, 7: 11176
[2] Zou P F, Wang H P, Yang S J, et al.Anomalous temperature dependence of liquid state density for Ni50Ti50 alloy investigated under electrostatic levitation state[J]. Chem. Phys. Lett., 2017, 681: 101
[3] Zhang S Z, Li C, Hou W T, et al.Longitudinal compression behavior of functionally graded Ti-6Al-4V meshes[J]. J. Mater. Sci. Technol., 2016, 32: 1098
[4] Zhao Z, Chen J, Guo S, et al.Influence of α/β interface phase on the tensile properties of laser cladding deposited Ti-6Al-4V titanium alloy[J]. J. Mater. Sci. Technol., 2017, 33: 675
[5] Liu H H, Niinomi M, Nakai M, et al.β-type titanium alloys for spinal fixation surgery with high Young's modulus variability and good mechanical properties[J]. Acta Biomater., 2015, 24: 361
[6] Kobryn P A, Moore E H, Semiatin S L.The effect of laser power and traverse speed on microstructure, porosity, and build height in laser-deposited Ti-6Al-4V[J]. Scr. Mater., 2000, 43: 299
[7] Thijs L, Verhaeghe F, Craeghs T, et al.A study of the microstructural evolution during selective laser melting of Ti-6Al-4V[J]. Acta Mater., 2010, 58: 3303
[8] Vrancken B, Thijs L, Kruth J P, et al.Heat treatment of Ti6Al4V produced by Selective Laser Melting: Microstructure and mechanical properties[J]. J. Alloys Compd., 2012, 541: 177
[9] He T, Hu R, Zhang T B, et al.Effect of Nb content on solidification characteristics and microsegregation in cast Ti-48Al-xNb alloys[J]. Acta Metall. Sin.(Engl. Lett.), 2016, 29: 714
[10] Liu Y, Hu R, Zhang T B, et al.Dendritic growth and microstructure evolution with different cooling rates in Ti-48Al-2Cr-2Nb alloy[J]. J. Mater. Eng. Perform., 2016, 25: 38
[11] Zhou K, Wei B.Determination of the thermophysical properties of liquid and solid Ti-6Al-4V alloy[J]. Appl. Phys., 2016, 122A: 248
[12] Wang H Y, Liu R P, Zhan Z J, et al.Dynamic and thermal computation of Fe-66.7%Si droplets free falling in a drop tube[J]. Acta Metall. Sin., 2005, 41: 940(王海燕, 刘日平, 战再吉等. Fe-66.7%Si合金液滴落管实验的动力学和传热学计算[J]. 金属学报, 2005, 41: 940)
[13] Oloyede O, Bigg T D, Cochrane R F, et al.Microstructure evolution and mechanical properties of drop-tube processed, rapidly solidified grey cast iron[J]. Mater. Sci. Eng., 2016, A654: 143
[14] Luo S B, Wang W L, Xia Z C, et al.Theoretical prediction and experimental observation for microstructural evolution of undercooled nickel-titanium eutectic type alloys[J]. J. Alloys Compd., 2017, 692: 265
[15] Wang G Q, Zhao Z B, Yu B B, et al.Effect of base material on microstructure and texture evolution of a Ti-6Al-4V electron-beam welded joint[J]. Acta Metall. Sin.(Engl. Lett.), 2017, 30: 499
[16] Broderick T F, Jackson A G, Jones H, et al.The effect of cooling conditions on the microstructure of rapidly solidified Ti-6Al-4V[J]. Metall. Mater. Trans., 1985, 16: 1951
[17] Ding R, Guo Z X, Wilson A.Microstructural evolution of a Ti-6Al-4V alloy during thermomechanical processing[J]. Mater. Sci. Eng., 2002, A327: 233
[18] Grant P S, Cantor B, Katgerman L.Modelling of droplet dynamic and thermal histories during spray forming—I. Individual droplet behavior[J]. Acta Metall. Mater., 1993, 41: 3097
[19] Lee E S, Ahn S.Solidification progress and heat transfer analysis of gas-atomized alloy droplets during spray forming[J]. Acta Metall. Mater., 1994, 42: 3231
[20] Xu Z Y.Martensitic Transformation and Martensite [M]. Beijing: Science Press, 1980: 29(徐祖耀. 马氏体相变与马氏体 [M]. 北京: 科学出版社, 1980: 29)
[21] Ramirez-Ledesma A L, Lopez-Molina E, Lopez H F, et al. Athermal ε-martensite transformation in a Co-20Cr alloy: Effect of rapid solidification on plate nucleation[J]. Acta Mater., 2016, 111: 138
[22] Ahmed T, Rack H J.Phase transformations during cooling in α+β titanium alloys[J]. Mater. Sci. Eng., 1998, A243: 206
[23] Peng X N, Guo H Z, Wang T, et al.Effects of β treatments on microstructures and mechanical properties of TC4-DT titanium alloy[J]. Mater. Sci. Eng., 2012, A533: 55
[24] Hrabe N, Quinn T.Effects of processing on microstructure and mechanical properties of a titanium alloy (Ti-6Al-4V) fabricated using electron beam melting (EBM), Part 2: Energy input, orientation, and location[J]. Mater. Sci. Eng., 2013, A573: 271
[25] Wu S Q, Lu Y J, Gan Y L, et al.Microstructural evolution and microhardness of a selective-laser-melted Ti-6Al-4V alloy after post heat treatments[J]. J. Alloys Compd., 2016, 672: 643
[26] Wang L, Su Y Q, Wang S J, et al.Effect of melt hydrogenation on structure and hardness of TC21 alloy[J]. Rare Met. Mater. Eng., 2011, 40: 321(王亮, 苏彦庆, 王书杰等. 液态置氢对TC21合金组织及硬度的影响[J]. 稀有金属材料与工程, 2011, 40: 321)
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