Elastic knowledge base of bcc Ti alloys from first-principles calculations and CALPHAD-based modeling

Journal Article · Fri Dec 01 00:00:00 EST 2017 · Computational Materials Science

DOI:https://doi.org/10.1016/j.commatsci.2017.08.037· OSTI ID:1462702

Marker, Cassie ^[1]; Shang, Shun-Li ^[1]; Zhao, Ji-Cheng ^[2]; Liu, Zi-Kui ^[1]

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1. The Pennsylvania State University, University Park, PA (United States). Department of Materials Science and Engineering
2. The Ohio State University, Columbus, OH (United States). Department of Materials Science and Engineering

Titanium alloys are being investigated as suitable materials for load-bearing implants because of theirbiocompatibility and mechanical properties. Stress shielding, a common issue with the current load-bearing implant materials, occurs due to a Young’s modulus (E) mismatch between bone (10–40 GPa)and implants (such as Ti-6Al-4V 110 GPa), which leads to bone dying around the implant and ultimatelyimplant failure. Reducing the Young’s modulus of Ti alloys may overcome the issues of stress shieldingand improve implant materials. In the present work, first-principles calculations have been used to pre-dict the single crystal elastic stiffness coefficients (cij’s) for the Ti-containing ternary alloys Ti-X-Y(X – Y = Mo, Nb, Sn, Ta, Zr) in the bcc lattice. It is found that the ternary Ti-X-Y (X – Y = Mo, Nb, Ta) alloysbehave similarly; so do the ternary Ti-X-Sn (X = Mo, Nb, Ta) alloys and the Ti-X-Zr (X = Mo, Nb, Ta) alloys.This is expected due to the similarity between the Mo, Nb and Ta elements. The results also show that theTi-Zr-X alloys stabilized the bcc phase at lower alloying concentrations. The polycrystalline aggregateproperties are also estimated from the cij’s, including bulk modulus, shear modulus and Young’s modulus.The results show that Ti-alloys with compositions close to the bcc stability limit have the lowest E.Incombination with previous predictions, a complete elastic database has been established using theCALPHAD (CALculation of PHAse Diagram) based modeling approach. The database results are comparedwith the E of higher order Ti alloys and shown to be able to predict the E accurately. This complete data-base forms a foundation to tailor Ti alloys for desired elastic properties.

• Research Organization: Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
• Sponsoring Organization: USDOE Office of Science (SC), Advanced Scientific Computing Research (ASCR)
• DOE Contract Number: AC02-05CH11231
• OSTI ID: 1462702
• Journal Information: Computational Materials Science, Vol. 140, Issue C; ISSN 0927-0256
• Publisher: Elsevier
• Country of Publication: United States
• Language: English