Institute of Fundamental Technological Research

In this paper, small-scale testing techniques—nanoindentation and micropillar compression—were used to investigate the deformation mechanisms, size effects, and strain rate sensitivity of (100) and (110) single-crystal Gum Metal at the micro/nanoscale. It was observed that the (100) orientation exhibits a significant size effect, resulting in hardness values ranging from 1 to 5 GPa. Conversely, for the (110) orientation, this effect was weaker. Furthermore, the yield strength obtained from the micropillar compression tests was approximately 740 MPa for the (100) orientation and 650 MPa for the (110) orientation. The observed deformations were consistent with the established features of the deformation behavior of body-centered cubic (bcc) alloys: significant strain rate sensitivity with no depth dependence, pile-up patterns comparable to those reported in the literature, and shear along the {112}<111> slip directions. However, the investigated material also exhibited Gum Metal-like high ductility, a relatively low modulus of elasticity, and high yield strength, which distinguishes it from classic bcc alloys.

The mechanical anisotropy of a multifunctional titanium alloy, Gum Metal, is investigated in this paper. The structural characterisation showed a strong <110> texture for Gum Metal, that is a result of the cold-swaging process applied during its manufacture. Gum Metal was treated as a transversally isotropic solid because of this texture. A significant difference from Young's moduli of the alloy was detected from the ultrasonic measurement of parallel and perpendicular directions to the alloy swaging direction. Samples of Gum Metal cubes were compressed in two different orientations. During the deformation process, two perpendicular walls of each sample were monitored by two visible range cameras for further two-dimensional digital image correlation analysis, this confirmed a strong plastic anisotropy in Gum Metal.

gum metal, compression, mechanical anisotropy, digital image correlation, ultrasonic measurement, texture, titanium alloy, full-field deformation measurement

Mechanical Anisotropy, Ti alloy, Gum Metal, Ultrasound Measurement, Digital Image Correlation

Gum Metal, Multifunctional Ti-based Alloy, Cyclic Compression, Infrared Thermography

Gum Metal, EBSD, ultrasonic measurement

Experimental investigation of mechanical anisotropy in a multifunctional beta titanium alloy Gum Metal under compression is reported. Non-destructive and destructive techniques were used to analyze unique mechanical behavior of the alloy. Structural characterization showed a strong <110> texture of Gum Metal, which is a result of cold-swaging applied during its fabrication [1]. Due to this kind of texture Gum Metal can be treated as transversally isotropic solid. Ultrasonic measurements determined elastic constants with high accuracy. A significant difference between Young's moduli of the alloy calculated for parallel and perpendicular directions to the alloy swaging direction was demonstrated. Compression of Gum Metal cube samples with two orientations was conducted on a testing machine. Two perpendicular walls of each sample were monitored by two visible range cameras during the deformation process for further 2-dimensional digital image correlation (DIC) analysis. Strong mechanical anisotropy of Gum Metal was confirmed by a detailed analysis of the stress vs. strain curves and strain distributions.

In this work, mechanical properties of a β-Ti alloy Gum Metal (Ti–23Nb–0.7Ta–2.0Zr–1.2O at.%, free of cytotoxic content), which was fabricated at Toyota Central Research&Development Laboratories, Inc., were investigated. It was confirmed that Gum Metal is characterized by a low Young's modulus (around 60 GPa), high strength (over 1000 MPa) and a large range of reversible deformation, which are important features in the context of potential implant applications. Moreover, a comprehensive assessment of biocompatibility was realized. Properties of Gum Metal were contrasted with those of Ti-6Al-4V (ELI) which was taken as reference. Surface conditions, such as topography, roughness and structural composition, were analyzed. Evaluation of biocompatibility for the alloys was performed by cell attachment and spreading analysis after predefined cell culture periods. Gum Metal presented excellent properties, what makes it a goodcandidate for implant applications.

Gum Metal, titanium alloy, biocompatibility, implant applications

Preliminary results of mechanical behavior of Gum Metal compressed along the swaging direction during cyclic loading were presented. The unique mechanical performance of Gum Metal - low Young’s Modulus and high strength were confirmed. During the cyclic loading the curves profiles change significantly with each cycle and reveal a clearly pronounced yield points for the 4th and further cycles. Compression tests along perpendicular direction to the swaging one will be considered for our future research.

Gum Metal, polycrystal, compression loading, cyclic loading, digital image correlation