NSUF 17-968: Post-irradiation characterization of ion irradiation damage in Ti-6Al-4V and CP-Ti : Influence of the microstructure and temperature

Due to their high specific strength, good fatigue and creep properties, corrosion resistance, as well as their commercial availability, titanium (Ti) alloys have been widely used in industrial, aerospace and biomedical applications. Titanium alloys are also extremely attractive for nuclear applications, being highly compatible with coolants (lithium, helium, water) and exhibiting low activation in radioactive environments. Ti-6Al-4V is considered as a candidate metal matrix for composite materials for the Next Generation Nuclear Reactors and as a structural material for the beam dump for the Facility for Rare Isotope Beams. The traditional manufacturing of Ti parts can be difficult, time consuming and have high material waste and manufacturing costs. Additive manufacturing presents an attractive alternative due to its capability to produce near-net shape components with less production time and material waste. Few TEM studies have investigated the irradiation damage in these Ti-alloys, specifically commercially available Ti-6Al-4V. A dual dose and temperature dependence was observed in the mechanical properties of Ti-6Al-4V irradiated with neutrons [1], protons [2] and swift heavy ions [3,4]; samples irradiated at higher temperature exhibited higher hardening at higher doses. The microstructure evolution under irradiation at 25°C and 350°C induced different obstacles to the dislocation motion and could explain this higher hardening at high temperature and doses. In these studies, only the final irradiated microstructure at a certain damage level was investigated, which leaves gaps in our understanding of the damage mechanisms. In-situ TEM irradiation offers the capability to investigate the evolution of the irradiation damage through continual imaging and observation. It allows for quantitative and qualitative microstructural studies. On the other hand, Ti-6Al-4V is also known for the dependence of its mechanical properties on the thermomechanical processing [5]. Thermomechanical processing influences the grain size and phase compositions. Improving the resistance of materials to irradiation damage has been, the subject of a few studies that focused on the effect of grain boundaries and grain size. A higher density of grain boundaries, such as in nanocrystalline materials, shows a higher irradiation resistance [6]. In addition, the effect of the grain size on irradiation-induced void formation was investigated in copper [7] and steel [8]. The effect of microstructure on the irradiation damage in Ti-6Al-4V has yet to be investigated. We are proposing a unique study that would investigate the difference between the irradiation damage in Ti-6Al-4V samples processed through two different thermomechanical processes: powder metallurgy (PM) rolled and additive manufacturing: direct metal laser sintered (DMLS) followed by hot isostatic pressing (HIP). This study would provide quantitative (defect formation, defect clustering, defect densities) and qualitative (defect interaction, defect motion, defect growth) results for irradiation damage at 350°C and room temperature. In addition the effect of dose rate will be investigated with two samples of CP-Ti. [1] S. Tähtinen, P. Moilanen, and B. N. Singh, J. Nucl. Mater., vol. 367–370, pp. 627–632, Aug. 2007. [2] P. Marmy and T. Leguey, J. Nucl. Mater., vol. 296, no. 1, pp. 155–164, 2001. [3] P. Wilkes and G. L. Kulcinski, J. Nucl. Mater., vol. 78, no. 2, pp. 427–430, 1978. [4] A. Amroussia et al., Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. At., Sep. 2015. [5] G. Lütjering and J. C. Williams, Titanium, vol. 2. Springer, 2003. [6] N. Nita et al., J. Nucl. Mater., vol. 329–333, pp. 953–957, Aug. 2004. [7] B. N. Singh et al., Mag. A, vol. 82, no. 6, pp. 1137–1158, Apr. 2002. [8] B. N. Singh, Philos. Mag., vol. 29, no. 1, pp. 25–42, Jan. 1974.

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Abstract	Due to their high specific strength, good fatigue and creep properties, corrosion resistance, as well as their commercial availability, titanium (Ti) alloys have been widely used in industrial, aerospace and biomedical applications. Titanium alloys are also extremely attractive for nuclear applications, being highly compatible with coolants (lithium, helium, water) and exhibiting low activation in radioactive environments. Ti-6Al-4V is considered as a candidate metal matrix for composite materials for the Next Generation Nuclear Reactors and as a structural material for the beam dump for the Facility for Rare Isotope Beams. The traditional manufacturing of Ti parts can be difficult, time consuming and have high material waste and manufacturing costs. Additive manufacturing presents an attractive alternative due to its capability to produce near-net shape components with less production time and material waste. Few TEM studies have investigated the irradiation damage in these Ti-alloys, specifically commercially available Ti-6Al-4V. A dual dose and temperature dependence was observed in the mechanical properties of Ti-6Al-4V irradiated with neutrons [1], protons [2] and swift heavy ions [3,4]; samples irradiated at higher temperature exhibited higher hardening at higher doses. The microstructure evolution under irradiation at 25°C and 350°C induced different obstacles to the dislocation motion and could explain this higher hardening at high temperature and doses. In these studies, only the final irradiated microstructure at a certain damage level was investigated, which leaves gaps in our understanding of the damage mechanisms. In-situ TEM irradiation offers the capability to investigate the evolution of the irradiation damage through continual imaging and observation. It allows for quantitative and qualitative microstructural studies. On the other hand, Ti-6Al-4V is also known for the dependence of its mechanical properties on the thermomechanical processing [5]. Thermomechanical processing influences the grain size and phase compositions. Improving the resistance of materials to irradiation damage has been, the subject of a few studies that focused on the effect of grain boundaries and grain size. A higher density of grain boundaries, such as in nanocrystalline materials, shows a higher irradiation resistance [6]. In addition, the effect of the grain size on irradiation-induced void formation was investigated in copper [7] and steel [8]. The effect of microstructure on the irradiation damage in Ti-6Al-4V has yet to be investigated. We are proposing a unique study that would investigate the difference between the irradiation damage in Ti-6Al-4V samples processed through two different thermomechanical processes: powder metallurgy (PM) rolled and additive manufacturing: direct metal laser sintered (DMLS) followed by hot isostatic pressing (HIP). This study would provide quantitative (defect formation, defect clustering, defect densities) and qualitative (defect interaction, defect motion, defect growth) results for irradiation damage at 350°C and room temperature. In addition the effect of dose rate will be investigated with two samples of CP-Ti. [1] S. Tähtinen, P. Moilanen, and B. N. Singh, J. Nucl. Mater., vol. 367–370, pp. 627–632, Aug. 2007. [2] P. Marmy and T. Leguey, J. Nucl. Mater., vol. 296, no. 1, pp. 155–164, 2001. [3] P. Wilkes and G. L. Kulcinski, J. Nucl. Mater., vol. 78, no. 2, pp. 427–430, 1978. [4] A. Amroussia et al., Nucl. Instrum. Methods Phys. Res. Sect. B Beam Interact. Mater. At., Sep. 2015. [5] G. Lütjering and J. C. Williams, Titanium, vol. 2. Springer, 2003. [6] N. Nita et al., J. Nucl. Mater., vol. 329–333, pp. 953–957, Aug. 2004. [7] B. N. Singh et al., Mag. A, vol. 82, no. 6, pp. 1137–1158, Apr. 2002. [8] B. N. Singh, Philos. Mag., vol. 29, no. 1, pp. 25–42, Jan. 1974.
Award Announced Date	2017-04-26T10:04:37.523
Awarded Institution	None
Facility	None
Facility Tech Lead	Kory Linton
Irradiation Facility	None
PI	Aida Amroussia
PI Email	[email protected]
Project Type	RTE
RTE Number	968