Study on Stability and Elastic Properties of β-TiX (X=Nb, Ta) Alloys From First-Principles Calculations

In this article, the phase stability, elastic properties, and electronic structure of the β-TiX (X = Nb, Ta) alloy body-centered cubic (bcc) structure were systematically studied with the aid of first-principles calculations. The results show that the phase stability and elastic properties of the β-TiX alloys are closely related to the contents of alloying element X. For β-TiX alloys, the contents of Nb and Ta that satisfy their mechanical stability are 10% and 13%, respectively; at room temperature, both β-TiNb and β-TiTa alloys can reach a thermodynamically stable state when the content of Nb or Ta is 25%. In terms of elastic properties, the content of alloying element X is positively correlated with the elastic constant, Young’s modulus, and shear modulus of the β-TiX alloys. The elastic modulus reaches its minimum when the X content is 25%, and the smallest direction of Young’s modulus appears in the <111> direction. The calculation results of the electronic structure show that the bonding strength between the Ti atom and X atom increases with the content of alloying element X, which leads to improvement of phase stability and elastic modulus

A Review of Effects of Femtosecond Laser Parameters on Metal Surface Properties

As a laser technology, the femtosecond laser is used in biomedical fields due to its excellent performance—its ultrashort pulses, high instantaneous power, and high precision. As a surface treatment process, the femtosecond laser can prepare different shapes on metal surfaces to enhance the material’s properties, such as its wear resistance, wetting, biocompatibility, etc. Laser-induced periodic surface structures (LIPSSs) are a common phenomenon that can be observed on almost any material after irradiation by a linearly polarized laser. In this paper, the current research state of LIPSSs in the field of biomedicine is reviewed. The influence of laser parameters (such as laser energy, pulse number, polarization state, and pulse duration) on the generation of LIPSSs is discussed. In this paper, the applications of LIPSSs by femtosecond laser modification for various purposes, such as in functional surfaces, the control of surface wettability, the surface colonization of cells, and the improvement of tribological properties of surfaces, are reviewed

Effect of low temperature pre-deformation on precipitation behavior and microstructure during fabrication

The effect of low-temperature pre-deformation on the microstructural evolution of a Zr–Sn–Nb–Fe–Cu–O alloy was investigated by optical metallography, scanning electron microscope, transmission electron microscope, and electron backscattering diffraction (EBSD). It is found that a reasonably homogeneous and fine equiaxed grain structure with uniformly distributed second-phase particles (SPPs) can be obtained in 40% pre-deformed samples (Group A) but not in directly hot-rolled ones (Group B) after hot rolling. The initial SPPs diameter in Group A is also reduced. Noticeable differences in microstructural evolutions including the distribution and size of SPPs, grain size of matrix, and texture are observed between both groups. Reasons for such discrepancies are attributed to the defects (such as dislocations and interfaces) introduced during the pre-deformation and more preferred precipitation sites formed in Group A. The aging after the pre-deformation results in new slip systems activated during hot rolling, leading to more thorough refinement of grains. In addition, the growth of SPPs is interpreted by the Lifshitz–Slyozov–Wagner model