Parameter Symbol Value Unit Temperature range/ ˚C References
Average radius of the particle at GB 1.0 μm - Min and Raj 18
Average size of grains d 40 μm - Min and Raj 18
Shear modulus G 7.6×1010 Pa - Min and Raj 18
Poisson’s ratio v 0.31 - - Min and Raj 18
Atom volume Ω 1.21×10-29 m3 - Min and Raj 18
Area fraction of the particles fb 0.2 - - Min and Raj 18
Shape factor related to the cavity volume Fv 0.1585 - - Raj and Ashby 14
Free surface formation energy γ 0.80 J.m-2 - Mortimer and Nicholas 31
Boltzmann constant k 1.3806×10-23 J.K-1 - Universal constant
Gas constant R 8.314 J.mole-1.K-1 - Universal constant
GB diffusion activation energy Qc 167×103 J.mole-1 - Frost and Ashby 30
GB thickness multiplied by its self-diffusion coefficient δDB 2.0×10-13exp(-Qc/RT) m3.s-1 - Frost and Ashby 30
Free surface diffusion coefficient* DS 9.0×10-7exp(-167×103/RT) m2.s-1 500-600 Not available in literature
Creep exponent n 11.83 - 500-600 Chen, Flewitt 29
Pre-exponential factor 1/ƞp 2.199×10-32 h-1.MPa-n 500 Chen, Flewitt 29
8.754×10-32 525
6.489×10-31 550
3.035×10-30 575
2.005×10-29 600