Abstract
Effects of normalizing and annealing treatments on the microstructure of Ti-48Al-2Cr-2Nb (at.%) were investigated. Normalizing processes were done at 1385 ± 5 °C in α-phase domain with the heating rate of 10 °C/min, the average cooling rate of 30 °C/min, and the holding times of 5, 10, 15, 20, and 25 min. The annealing process was done at the same temperature and heating rate, the holding time of 15 min, and the average cooling rate of 2 °C/min. Microstructures, phases, and hardness levels were studied by optical and field emission electron microscopic observations, x-ray diffractometry (XRD), and microhardness testing, respectively. Also, crystallographic texture variations were analyzed by means of texture coefficient and XRD results. Experimental results showed a linear direct relationship between treatment time and grain size, up to 15 min. A linear reversed behavior was observed for longer times. The untreated alloy consisted of γ and α2 phases with a columnar morphology with the length of about 300 μm. A near-lamellar microstructure with equiaxed gamma grains, Widmansttäten, and laminar γ + α2 colonies was obtained by the normalizing process. The maximum reduction of the grain size was about 70%, as achieved by normalizing with the 15 min holding time. A texture-free microstructure was acquired by normalizing treatment in comparison with strong texture of the as-cast and annealed alloys.
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D. Hu, X. Wu, and M.H. Loretto, Advances in Optimisation of Mechanical Properties in Cast TiAl Alloys, Intermetallics, 2005, 13, p 914–919
A. Sankaran, E. Bouzy, J.J. Fundenberger and A. Hazotte, Texture and Microstructure Evolution During Tempering of Gamma-Massive Phase in a TiAl-Based Alloy, Intermetallics, 2009, 17, p 1007–1016
D. Eatesami, S.M. Hadavi, and A. Habibollahzade, Melting of γ -TiAl in the Alumina Crucible, Rus. J. Nonferr. Metals, 2009, 50, p 363–367
W.C. Xu, D.B. Shan, H. Zhang, X.A. Li, Y.Z. Zhang, and S. Nutt, Effects of Extrusion Deformation on Microstructure, Mechanical Properties and Hot Workability of β Containing TiAl Alloy, J. Mater. Sci. Eng. A, 2013, 571, p 199–206
B. Tang, L. Cheng, H. Kou, and J. Li, Hot Forging Design and Microstructure Evolution of a High Nb Containing TiAl Alloy, Intermetallics, 2015, 58, p 7–14
A.R. Kamali, S.M. Hadavi, and H. Razavizadeh, Production of Ti-8Al-1Mo-1V Alloy by Using of New Master Alloys, Int. J. Mater. Sci., 2008, 3(1), p 61–67
A. Bartels and W. Schillinger, Micromechanical Mechanism of Texture Formation in γ–TiAl, Intermetallics, 2001, 9, p 883–889
A. Bartels, H. Kestler, and H. Clemens, Deformation Behavior of Differently Processed γ-Titanium Aluminides, Mater. Sci. Eng. A, 2002, 329, p 153–162
R. Ding, H. Li, D. Hu, N. Martin, M. Dixon, and P. Bowen, Features of Fracture Surface in a Fully Lamellar TiAl-Base Alloy, Intermetallics, 2015, 58, p 36–42
H.Z. Niu, Y.Y. Chen, Y.S. Zhang, J.W. Lu, W. Zhang, and P.X. Zhang, Producing Fully-Lamellar Microstructure for Wrought Beta-Gamma TiAl Alloys Without Single α-Phase Field, Intermetallics, 2015, 59, p 87–94
K. Kothari, R. Radhakrishnan, and N. Wereley, Advances in Gamma Titanium Aluminides and Their Manufacturing Techniques, Prog. Aeronaut. Sci., 2012, 55, p 1–16
H. Zhu, D.Y. Seo, K. Maruyama, and P. Au, Effect of Lamellar Spacing on Microstructural Instability and Creep Behavior of a Lamellar TiAl Alloy, Scr. Mater., 2006, 54, p 1979–1984
Y. Mine, K. Takashima, and P. Bowen, Effect of Lamellar Spacing on Fatigue Crack Growth Behaviour of a TiAl-Based Aluminide with Lamellar Microstructure, J. Mater. Sci. Eng. A, 2012, 532, p 13–20
E. Schwaighofer, H. Clemens, S. Mayer, J. Lindemann, J. Klose, W. Smarsly, and V. Güther, Microstructural Design and Mechanical Properties of a Cast and Heat Treated Intermetallic Multi-phase γ -TiAl Based Alloy, Intermetallics, 2014, 44, p 128–140
J. Yang, J.N. Wang, Q. Xia, and Y. Wang, Effect of Cooling Rate on the Grain Refinement of TiAl-Based Alloys by Rapid Heat Treatment, Mater. Lett., 2000, 46, p 193–197
A. Koscieln and W. Szkliniarz, Effect of Cyclic Heat Treatment Parameters on the Grain Refinement of Ti–48Al–2Cr–2Nb Alloy, Mater. Charact., 2009, 60, p 1158–1162
J.N. Wang, J. Yang, and Y. Wang, Grain Refinement of a Ti–47Al–8Nb–2Cr Alloy Through Heat Treatments, Scr. Mater., 2005, 52, p 329–334
W.J. Zhang, G.L. Chen, and E. Evangelista, Formation of α Phase in the Massive and Feathery γ-TiAl Alloys During Aging in the Single α Field, Metall. Mater. Trans. A, 1999, 30, p 2591–2598
Y.W. Kim and S.L. Kim, Effects of Microstructure and C and Si Additions on Elevated Temperature Creep and Fatigue of Gamma TiAl Alloys, Intermetallics, 2014, 53, p 92–101
A. Denquint and S. Naka, Phase Transformation Mechanisms Involved in Two-Phase TiAl- Based Alloy-Lamellar Structure Formation, Acta Metall. Mater., 1996, 44(1), p 343–356
S.R. De, A. Hazotte, E. Bouz, and S. Naka, Development of Widmanstätten Laths in a Near- γ TiAl Alloy, Acta Mater., 2005, 53, p 3783–3794
M. Charpentier, A. Hazotte, and D. Daloz, Lamellar Transformation in Near γ - TiAl Alloys—Quantitative Analysis of Kinetics and Microstructure, Mater. Sci. Eng. A, 2008, 491, p 321–330
Y.G. Zhang and M.C. Chaturvedi, The Effect of Widmanstätten-Type α2 Precipitates on Room Temperature Deformation and Fracture Behaviour of a γ-TiAl-Based Alloy, J. Mater. Sci. Eng. A, 1994, 174(1), p 45–57
Y. Wang, W. Tang, and L. Zhang, Crystalline Size Effects on Texture Coefficient, Electrical and Optical Properties of Sputter-Deposited Ga-Doped ZnO Thin Films, J. Mater. Sci. Technol., 2015, 31(2), p 175–181
D. Abson and J. Jonas, The Hall-Petch Relation and High-Temperature Subgrains, Metal. Sci. J., 1970, 4, p 24–32
R.J. Hill and C.J. Howard, Quantitative Phase Analysis from Neutron Powder Diffraction Data Using the Rietveld Method, J. Appl. Cryst., 1987, 20, p 467–474
M.J. Blackburn, Some Aspects of Phase Transformations in Titanium Alloys, The Science, Technology and Applications of Titanium, 1st ed., R.I. Jaffee and N.E. Promisel, Ed., May 21-24, 1968 (London), Pergamon Press, 1970, p 633–643
S.R. Dey, E. Bouzy, and A. Hazotte, Features of Feathery γ Structure in a Near-γ TiAl Alloy, Acta Mater., 2008, 56, p 2051–2062
M. Yamaguchi, D.R. Johnson, H.N. Lee, and H. Inui, Directional Solidification of TiAl-Base Alloys, Intermetallics, 2000, 8, p 511–517
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Ahmadi, M., Hosseini, S.R. & Hadavi, S.M.M. Effects of Heat Treatment on Microstructural Modification of As-Cast Gamma-TiAl Alloy. J. of Materi Eng and Perform 25, 2138–2146 (2016). https://doi.org/10.1007/s11665-016-2067-7
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DOI: https://doi.org/10.1007/s11665-016-2067-7