Multicomponent, biomedical β-Ti alloys offer ultra-low Young modulus values that are related to a unique and poorly understood reduction of C₄₄ and C′ elastic constants in comparison with binary systems. The elastic properties of such materials are difficult to control due to the large variations occurring even for a small change in chemical composition, which cannot be explained using existing theories. In this article, we investigate the above issues through systematic ab initio elastic constants calculations for a series of binary, ternary and quaternary Ti alloys. Special attention is paid to examining the reliability of the methodology adopted and to clarifying the atomic scale mechanisms that affect the mechanical properties of the systems analysed. It was found that the lower boundary of the polycrystalline Young modulus of Ti-Nb-base β phase is close to 50 GPa, and strongly depends on two specific electronic hybridisations related to niobium and simple metals addition that control C₄₄ and C′. Based on the relationship established between electronic structure and mechanical properties, we propose several quaternary alloys whose directional <100> Young modulus values are equal or similar to that of human bones. Some electronic-based guidelines for designing new multicomponent β-Ti alloys are also formulated.

多组分生物医学β-Ti合金具有极低的杨氏模量值，这与C ₄₄和C'的独特且难以理解的降低有关与二元系统相比的弹性常数。由于即使对于化学成分的微小变化也会发生较大的变化，因此这种材料的弹性性质难以控制，这不能用现有的理论来解释。在本文中，我们通过系统地从头算弹性常数计算一系列二元，三元和四元Ti合金来研究上述问题。要特别注意检查所采用方法的可靠性，并阐明影响所分析系统机械性能的原子尺度机理。发现Ti-Nb基β相的多晶杨氏模量的下边界接近50 GPa，并且强烈地依赖于与铌有关的两种特定的电子杂交和控制添加的简单金属C ₄₄和C'。基于建立的电子结构与力学性能之间的关系，我们提出了几种方向<100>杨氏模量值与人体骨骼相同或相似的四元合金。还制定了一些用于设计新型多组分β-Ti合金的基于电子的指南。