Verifying the cytotoxicity of a biodegradable zinc alloy with nanodiamond sensors.

Metals are widely utilized as implant materials for bone fixtures as well as stents. Biodegradable versions of these implants are highly desirable since patients do not have to undergo a second surgery for the materials to be removed. Attractive options for such materials are zinc silver alloys since they also offer the benefit of being antibacterial.

Can Severe Plastic Deformation Tune Nanocrystallization in Fe-Based Metallic Glasses?

The effects of severe plastic deformation (SPD) by means of high-pressure torsion (HPT) on the structural properties of the two iron-based metallic glasses FeCuNbSiB and FeCoSiBPCu have been investigated and compared. While for FeCuNbSiB, HPT processing allows us to extend the known consolidation and deformation ranges, HPT processing of FeCoSiBPCu for the first time ever achieves consolidation and deformation with a minimum number of cracks. Using numerous analyses such as X-ray diffraction, dynamic mechanical analyses, and differential scanning calorimetry, as well as optical and transmission electron microscopy, clearly reveals that FeCoSiBPCu exhibits HPT-induced crystallization phenomena, while FeCuNbSiB does not crystallize even at the highest HPT-deformation degrees applied.

Enhancing the Mechanical Properties of Biodegradable Mg Alloys Processed by Warm HPT and Thermal Treatments.

In this study, several biodegradable Mg alloys (Mg5Zn, Mg5Zn0.3Ca, Mg5Zn0.15Ca, and Mg5Zn0.

Surface Analysis of Biodegradable Mg-Alloys after Immersion in Simulated Body Fluid.

Two binary biodegradable Mg-alloys and one ternary biodegradable Mg-alloy (Mg-0.3Ca, Mg-5Zn and Mg-5Zn-0.3Ca, all in wt%) were investigated.

Exceptional Strengthening of Biodegradable Mg-Zn-Ca Alloys through High Pressure Torsion and Subsequent Heat Treatment.

In this study, two biodegradable Mg-Zn-Ca alloys with alloy content of less than 1 wt % were strengthened via high pressure torsion (HPT). A subsequent heat treatment at temperatures of around 0.45 led to an additional, sometimes even larger increase in both hardness and tensile strength.

Giant thermal expansion and α-precipitation pathways in Ti-alloys.

Ti-alloys represent the principal structural materials in both aerospace development and metallic biomaterials. Key to optimizing their mechanical and functional behaviour is in-depth know-how of their phases and the complex interplay of diffusive vs. displacive phase transformations to permit the tailoring of intricate microstructures across a wide spectrum of configurations.

Mechanical properties, structural and texture evolution of biocompatible Ti-45Nb alloy processed by severe plastic deformation.

Biocompatible β Ti-45Nb (wt%) alloys were subjected to different methods of severe plastic deformation (SPD) in order to increase the mechanical strength without increasing the low Young׳s modulus thus avoiding the stress shielding effect. The mechanical properties, microstructural changes and texture evolution were investigated, by means of tensile, microhardness and nanoindentation tests, as well as TEM and XRD. Significant increases of hardness and ultimate tensile strength up to a factor 1.

Changes in microstructure and physical properties of skutterudites after severe plastic deformation.

The best p-type skutterudites with ZT > 1.1 so far are didymium (DD) filled, Fe/Co substituted, Sb-based skutterudites. DD0.

Thermal stability and phase transformations of martensitic Ti-Nb alloys.

Aiming at understanding the governing microstructural phenomena during heat treatments of Ni-free Ti-based shape memory materials for biomedical applications, a series of Ti-Nb alloys with Nb concentrations up to 29 wt% was produced by cold-crucible casting, followed by homogenization treatment and water quenching. Despite the large amount of literature available concerning the thermal stability and ageing behavior of Ti-Nb alloys, only few studies were performed dealing with the isochronal transformation behavior of initially martensitic Ti-Nb alloys. In this work, the formation of martensites (' and ″) and their stability under different thermal processing conditions were investigated by a combination of x-ray diffraction, differential scanning calorimetry, dilatometry and electron microscopy.

Direct experimental determination of grain boundary excess volume in metals.

The grain boundary excess volume, i.e., the grain boundary expansion, e{GB}, was experimentally determined for high-angle grain boundaries in nickel using the direct technique of high-precision difference dilatometry.

Absolute concentration of free volume-type defects in ultrafine-grained Fe prepared by high-pressure torsion.

A maximum excess volume ΔV/V ≈ 1.9 × 10(-3) in ultrafine-grained Fe prepared by high-pressure torsion is determined by measurements of the irreversible length change upon annealing employing a high-resolution differential dilatometer. Since dislocations and equilibrium-type grain boundaries cannot fully account for the observed released excess volume, the present study yields evidence for a high concentration of free volume-type defects inherent to nanophase materials, which is considered to be the main source of their particular properties, such as strongly enhanced diffusivities.

In situ probing of fast defect annealing in Cu and Ni with a high-intensity positron beam.

A high-intensity positron beam is used for specific in situ monitoring of thermally activated fast defect annealing in Cu and Ni on a time scale of minutes. The atomistic technique of positron-electron annihilation is combined with macroscopic high-precision length-change measurements under the same thermal conditions. The combination of these two methods as demonstrated in this case study allows for a detailed analysis of multistage defect annealing in solids distinguishing vacancies, dislocations, and grain growth.