The Temperature‐Dependent Ideal Tensile Strength of ZrB₂, HfB₂, and TiB₂

Abstract

This paper is aimed to fill the void in the literature regarding the temperature-dependent ideal tensile strength of the AlB 2 -like diborides. To this end, two models of temperature-dependent ideal tensile strength of hexagonal single crystals are developed based on the critical failure energy density principle and the critical strain principle. The two models relate the ideal tensile strength to the elastic properties, thermal expansion, and specific heat at constant pressure of single crystals. The temperature-dependent uniaxial ideal tensile strengths of ZrB 2 , HfB 2 , and TiB 2 are predicted. The predictions from the critical strain principle agree well with that from the critical failure energy density principle. The study shows that the temperature dependence of the ideal tensile strength is similar to that of Young's modulus. That is, the ideal tensile strength firstly remains approximately constant and then decreases linearly as temperature increases. The fracture failure for hexagonal single crystals at elevated temperatures is identified as a strain-controlled criterion for the first time.

Thermal shock fracture of a cylinder with a penny-shaped crack based on hyperbolic heat conduction

“…(10) in Laplace transform consists of the homogeneous solution and a particular solution. The homogeneous solution, which is independent of temperature, can be found through Hankel transform with respect to variable r. It is given as:…”

“…[7][8][9][10] use temperaturedependent material properties and Ref. [11] studies the heat transfer in skin tissues).…”

Grain boundary driven mechanical properties of ZrB2 and ZrC‐ZrB2 nanocomposite: A molecular simulation study

“…The computed tensile strengths of both ZrB 2 and ZrB 2 ‐ZrC nanocomposite are about 22 GPa. In essence, the estimated strength values are roughly half of the ideal tensile strength of ZrB 2 but at least 2 orders of magnitude higher than the experimentally obtained strengths of ZrB 2 (250‐630 MPa) . As outlined in Fahrenholtz et al, the as‐fabricated of ZrB 2 and ZrB 2 ‐10 vol% ZrC composites contain flaws of different types and sizes, which most likely contribute to low mechanical strengths.…”

“…To improve oxidation resistance, thermal stability, and mechanical properties, other ceramic phases such as ZrC and silicon carbide (SiC) are often added to ZrB 2. Reactive hot pressing and pressureless sintering methods are primarily used to process these materials.…”

Effect of Ni content on microstructures and mechanical properties of hot-pressed TiC–TiB2–Ni composite

“…Both TiC and TiB 2 possess high melting point and hardness, good electroconductivity and thermal conductivity, excellent chemical and thermal stability as well as low thermal expansivity [1][2][3][4][5]. Compared to TiC or TiB 2 single phase ceramics, TiC-TiB 2 composite ceramics not only combine both the characteristics of TiC and TiB 2 [6,7], but also show more excellent physical and mechanical properties [8,9].…”