Hot deformation behavior of Cu-bearing antibacterial titanium alloy

doi:10.1016/j.jmst.2017.12.015

Abstract

Abstract:

We investigated the deformation behavior of a new biomedical Cu-bearing titanium alloy (Ti-645 (Ti-6.06Al-3.75V-4.85Cu, in wt%)) to optimize its microstructure control and the hot-working process. The results showed that true stress-true strain curve of Ti-645 alloy was susceptible to both deformation temperature and strain rate. The microstructure of Ti-645 alloy was significantly changed from equiaxed grain to acicular one with the deformation temperature while a notable decrease in grain size was recorded as well. Dynamic recovery (DRV) and dynamic recrystallization (DRX) obviously existed during the thermal compression of Ti-645 alloy. The apparent activation energies in (α + β) phase and β single phase regions were calculated to be 495.21 kJ mol^-1 and 195.69 kJ mol^-1, respectively. The processing map showed that the alloy had a large hot-working region whereas the optimum window occurred in the strain rate range of 0.001-0.1 s^-1, and temperature range of 900-960 °C and 1000-1050 °C. The obtained results could provide a technological basis for the design of hot working procedure of Ti-645 alloy to optimize the material design and widen the potential application of Ti-645 alloy in clinic.

Key words: Cu-bearing titanium alloy, Constitutive equation, Thermal deformation, Microstructure, Processing map

Zheng Ma, Ling Ren, M. Babar Shahzad, Rui Liu, Ying Zhao, Ke Yang. Hot deformation behavior of Cu-bearing antibacterial titanium alloy[J]. J. Mater. Sci. Technol., 2018, 34(10): 1867-1875.

Figures/Tables 12

Table 1 Composition of Ti-645 alloy (wt%).

Alloy	Al	V	Cu	Fe	C	N	O	H	Ti
Ti-645	6.06	3.75	4.85	0.06	0.01	0.002	0.05	0.001	Balance

Fig 1. True stress-strain curves of Ti-645 alloy at given strain rates and temperatures.

Fig. 2. Functional relationship of (a) lnσ-ln ?, (b) σ-ln ?, and (c) ln(sinh(ασ))-ln? in α+β and β regions.

Fig. 3. Functional relationship between ln(sinh(ασ)) and temperature in (α+β) and β regions at the strain of 0.6.

Fig. 4. Functional relationship between flow stress and Z parameter during hot deformation of Ti-645 alloy.

Fig. 5. PM of Ti-645 alloy.

Fig. 6. Microstructures of Ti-645 alloy for hot compression tests: (a) at a low magnification, (b) at a high magnification.

Fig. 7. Optical microstructures of Ti-645 alloy deformed at 800 °C with strain rates of (a) 0.001 s-1, (b) 0.01 s-1, (c) 0. 1 s-1, (d) 1 s-1 and (e) 10 s-1.

Fig. 8. SEM microstructures of Ti-645 alloy deformed at 800 °C with strain rates of (a) 0.001 s-1, (b) 0.01 s-1, (c) 0.1 s-1, (d) 1 s-1, (e) 10 s-1, red circle representing the recrystallization zone and red arrows showing the irregular grain boundaries.

Fig. 9. SEM microstructures of Ti-645 alloy deformed at strain rate of 0.01 s-1 and temperatures of (a) 800 °C, red dotted lines representing the globularized α, (b) 850 °C, red dotted line representing elongated globularized grain, (c) 900 °C, (d) 950 °C, red arrows showing the straight grain boundaries, (e) 1000 °C and (f) 1050 °C. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 10. Typical microstructures of Ti-645 alloy after hot compression under different conditions, (a) 850 °C/1 s-1, red dotted lines representing zigzag grain, (b) 950 °C/10 s-1, (c) 1050 °C/1 s-1, (d) 800 °C/0.01 s-1, red circle representing the globularized α, (e) 950 °C/0.01 s-1, red arrows showing the straight grain boundaries, and (f) 1050 °C/0.01 s-1. (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

Fig. 11. TEM images of Ti-645 alloy after hot compression under different conditions: (a) 850 °C/1 s-1, (b) 950 °C/10 s-1, (c) 950 °C/0.01 s-1 and (d) 1050 °C/0.01 s-1.

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