In this study, five MgZnCa alloys with low alloy content and high biocorrosion resistance were investigated during thermomechanical processing. As documented by microhardness and tensile tests, high pressure torsion (HPT)-processing and subsequent heat treatments led to strength increases of up to 250%; as much as about 1/3 of this increase was due to the heat treatment. Microstructural analyses by electron microscopy revealed a significant density of precipitates, but estimates of the Orowan strength exhibited values much smaller than the strength increases observed. Calculations using Kirchner’s model of vacancy hardening, however, showed that vacancy concentrations of 10⁻⁵ could have accounted for the extensive hardening observed, at least when they formed vacancy agglomerates with sizes around 50‒100 nm. While such an effect has been suggested for a selected Mg-alloy already in a previous paper of the authors, in this study the effect was substantiated by combined quantitative evaluations from differential scanning calorimetry and X-ray line profile analysis. Those exhibited vacancy concentrations of up to about 10⁻³ with a marked percentage being part of vacancy agglomerates, which has been confirmed by evaluations of defect specific activation migration enthalpies. The variations of Young’s modulus during HPT-processing and during the subsequent thermal treatments were small. Additionally, the corrosion rate did not markedly change compared to that of the homogenized state.

中文翻译：

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严重的塑性变形和/或热处理对可生物降解镁合金力学性能的影响

在这项研究中，研究了五种具有低合金含量和高抗生物腐蚀性的MgZnCa合金。正如显微硬度和拉伸试验所证明的那样，高压扭转（HPT）处理和后续热处理导致强度提高了250％。大约有1/3的增加是由于热处理造成的。通过电子显微镜进行的微结构分析显示出显着的沉淀物密度，但是对Orowan强度的估计显示出的值远小于观察到的强度增加。利用空置硬化基什内尔的模型计算，然而，结果显示，10空位浓度^-⁵可能是观察到的广泛硬化的原因，至少当它们形成尺寸为50‒100 nm左右的空洞附聚物时。尽管已经在作者的前一篇论文中针对选定的镁合金提出了这种效果，但在本研究中，该效果通过差示扫描量热法和X射线谱线分析的组合定量评估得到了证实。那些表现出高达约10 ^-3的空位浓度，其中显着的百分比是空位附聚物的一部分，这已经通过评估缺陷特异性活化迁移焓而得到证实。在HPT处理过程中和随后的热处理过程中，杨氏模量的变化很小。另外，与均质状态相比，腐蚀速率没有明显变化。