With the assumption that both size‐ and strain‐broadened profiles of the pure‐specimen function are described with a Voigt function, it is shown that the analysis of Fourier coefficients leads to the Warren–Averbach method of separation of size and strain contributions. The analysis of size coefficients shows that the `hook' effect occurs when the Cauchy content of the size‐broadened profile is underestimated. The ratio of volume‐weighted and surface‐weighted domain sizes can change from ~1.31, for the minimum allowed Cauchy content, to 2, when the size‐broadened profile is given solely by a Cauchy function. If the distortion Subscripts coefficient is approximated by a harmonic term, mean‐square strains decrease linearly with increasing the averaging distance. The local strain is finite only in the case of purely Gaussian strain broadening, because strains are then independent of averaging distance.
We constructed computer-based simulations of the lattice dynamical properties of plutonium using an electronic structure method, which incorporates correlation effects among the f-shell electrons and calculates phonon spectra at arbitrary wavelengths. Our predicted spectrum for the face-centered cubic delta phase agrees well with experiments in the elastic limit and explains unusually large shear anisotropy of this material. The spectrum of the body-centered cubic phase shows an instability at zero temperature over a broad region of the wave vectors, indicating that this phase is highly anharmonic and can be stabilized at high temperatures by its phonon entropy.
A comprehensive compilation is ~ven of elastic properties of iron-nickel alloys. When sufficient data exist, preferred values are recommended_ This compilation covers, besides pure iron and pure nickel, the entire binary composition range, both b.c_c. and f.c.c. phases. Elastic constants included are: Young's modulus, shear modulus, bulk modulus (reciprocal compressibility), Poisson's ratio, and singlecrystal elastic stiffnesses, both second-order and higher-order. Data are compiled for variation of ela~tic com;tant<;. with rompo!>.ition, tpmpprlltllre, prp!>.!>.nrp., magnetic neld. mechanical deformation.annealing, and crystallographic transitions. An overview is given f~om the vantage points of the electron theory ·of m.etals, elasticity theory, and crystallographic theory. Also included are discussions of isothermal and adiabatic elastic constants, interrelationships among engineering elastic constants, computation of the latter from single-crystal elastic stiffnesses, and similar topics. Where key data have not been measured, they were generated if possible from existing data using standard formulae. Other gaps, both theoretical and experimental, in the elastic properties of iron-nickel alloys are indicated. A few theoretical results are included where experimental data are nonexistent or scarce. A semantic scheme is proposed for distinguishing elastic constants of solids.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.