Thermodynamic Investigations Of Biomedical Titanium Alloys

New material design and development are always being hotspots of materials research.Phase diagram is called the “sole diagram” of materials design.It can directly reflect the relationship between material compositions,structures and properties,which plays a pivotal role in materials research.The present work focuses on the key material systems of biomedical Ti alloys(Ti-Zn binary,Ti-Al-Zr ternary and Ti-NbHf-C quaternary system),and attempts to establish a series of self-consistent thermodynamic database by key experiments,ab initio calculations and CALPHAD method.Aiming to provide the thermodynamics theoretical basis for biomedical titanium alloys design.The major research contents of the present work are as follows:(1)The thermodynamic data and phase diagram information of the Ti-Zn system in literature were critically evaluated.Coupling key experiments,ab initio calculations and CALPHAD method,the Ti-Zn binary phase diagram was re-constructed.(2)On the basis of the reported thermodynamic data and phase diagram information,a set of self-consistent thermodynamic parameters for the Ti-Al-Zr system was obtained via ab initio calculations and CALPHAD methods for the first time.(3)Each sub-binary system and sub-ternary system in the Ti-Nb-Hf-C system were carefully assessed.A thermodynamic database of the quaternary Ti-Nb-Hf-C system was established,and all the experimental data can be reproduced reasonably by the present calculations.(4)Finally,taking the Ti-Al-Zr ternary system as an example.Based on the thermodynamic database of the Ti-Al-Zr system,the mechanical properties of specified Ti-Al-Zr alloys were studied by ab initio calculations and stress-strain method.A big dataset of “Atomic arrangement-Alloy composition-Synthesis temperature-Phase structure-Elastic modulus” of the Ti-Al-Zr alloys was constructed,which can provide a theoretical basis for the design of related new materials.