The β-phase stability and deformation behavior patterns of two β-type titanium bioalloys, viz. Ti-Nb-Ta-Zr (TNTZ) type and Ti-Nb-Ta (TNT) type, processed by a series of intense plastic deformations have been investigated theoretically and experimentally. Firstly, theoretical analysis was carried out, including an estimation of possible deformation mechanisms based on the electronic parameters of the studied alloys identified with the aid of the Bo–Md diagram. Secondly, phase composition and structural parameters determined by x-ray diffraction (XRD) analysis revealed that the application of severe plastic deformation (SPD) induces grain refinement (in particular for one of the two alloys), accompanied by residual stress generation and some partial phase transformation. Scanning electron microscopy (SEM)/transmission electron microscopy (TEM) imaging and some measurements of the texture completed the deformation behavior analysis. TNT alloy, with higher β stability (Mo_eq ~ 12.5 wt.%), presented an almost unmodified β-grain dimension from 29.4 nm to 24.4 nm (and thus poor β-grain refinement), coupled with a very fine dispersion of nanometric (~ 8.4 nm) crystallites of orthorhombic α″-stress-induced martensite. TNTZ alloy, also with high β stability (Mo_eq ~ 10.1 wt.%), showed accentuated β-grain refinement (from 27.8 nm to 9.9 nm), with a very small amount of orthorhombic α″-stress-induced martensite, but grain dimensions almost three times larger than that of the TNT alloy (~ 20.8 nm). The theoretical estimations concerning the possible deformation mechanisms are supported by the analysis of the experimental results.

中文翻译：

---

两种生物医学β钛合金在严重塑性变形过程中的β相稳定性

两个β的β相稳定性和变形行为模式型钛生物合金，即。从理论和实验上研究了通过一系列强烈塑性变形处理的Ti-Nb-Ta-Zr（TNTZ）型和Ti-Nb-Ta（TNT）型。首先，进行了理论分析，包括根据通过Bo–Md图鉴定的被研究合金的电子参数估算可能的变形机制。其次，通过X射线衍射（XRD）分析确定的相组成和结构参数表明，严重的塑性变形（SPD）的应用引起晶粒细化（特别是对于两种合金之一），伴随有残余应力的产生和一些局部应力。相变。扫描电子显微镜（SEM）/透射电子显微镜（TEM）成像和一些纹理测量完成了变形行为分析。TNT合金，更高β稳定性（莫_当量 〜12.5重量％），提出了一种几乎未修饰的β -grain尺寸从29.4纳米至24.4纳米（且因此差β -grain细化），加上纳米的非常细的分散体（〜8.4纳米）的微晶斜方晶α ”应力诱发的马氏体。TNTZ合金，也具有高β稳定性（莫_当量 〜10.1重量％），显示出突出β -grain细化（从27.8纳米至9.9纳米），具有正交的一个非常小的量α应力诱导的马氏体，但晶粒尺寸几乎是TNT合金（〜20.8 nm）的三倍。对可能的变形机理的理论估计得到了实验结果分析的支持。