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Creep of TiB2

Deformation of a polycrystalline ceramic under sustained loading at high temperature produces creep, i.e., a strain that increases monotonically with time. A plot of strain vs time typically has three distinguishable regions denoted as a primary, secondary, and tertiary creep. While numerous mechanisms capable of producing creep have been identified, the principal mechanisms for creep in high-purity polycrystalline ceramics are considered solid-state diffusional mechanisms. The secondary (also called steady-state) creep rate, dϵ/dt, for diffusional and dislocation] mechanisms is often expressed in the form of the Norton model. dϵdt=A(σ/σ0)nexp[−Q/RT], where the amplitude factor A, the stress exponent n, and the apparent activation energy Q are adjustable parameters,σ0 is a fixed scale factor that may be taken to be 1 MPa, and R = 8.31451 J mol−1 K−1 is the molar gas constant. This model is valid for specimens with a constant grain size if log(dϵ/dt) is linearly proportional to 1/T and the plots for various fixed values of the applied stress σ are parallel. These conditions are satisfied approximately by the flexural creep data of TiB2. Applying these data, the parameters may be evaluated as A = 4.806×10−4 s−1, n = 2.3, and Q = 426 kJ/mol for ρ = 4.29 g/cm3 and g = 18 μm. With these parameters, the relative standard uncertainty of log(dϵ/dt) is 20 % based on the statistical standard deviation of the fit. If you are looking for high quality, high purity, and cost-effective Titanium diboride, or if you require the latest price of Titanium diboride, please feel free to email contact mis-asia.

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