Dislocation interaction with C in alpha-Fe: a comparison between atomic simulations and elasticity theory

The interaction of C atoms with a screw and an edge dislocation is modelled at an atomic scale using an empirical Fe-C interatomic potential based on the Embedded Atom Method (EAM) and molecular statics simulations. Results of atomic simulations are compared with predictions of elasticity theory. It is shown that a quantitative agreement can be obtained between both modelling techniques as long as anisotropic elastic calculations are performed and both the dilatation and the tetragonal distortion induced by the C interstitial are considered. Using isotropic elasticity allows to predict the main trends of the interaction and considering only the interstitial dilatation will lead to a wrong interaction

Hydrogen adsorption at dislocations and cracks in Fe

Solute adsorption to dislocations and cracks is considered in both the Boltzmann and Fermi-Dirac models. Explicit sums are developed for the integral amount of solute adsorbed in the defect fields. Examples of the use of the method are presented for the case of hydrogen in iron and compared with earlier results. The similarity of the condensed atmosphere of hydrogen to hydride precipitation is noted and its relevancy to hydrogen embrittlement models is discussed.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/22483/1/0000024.pd

NACA Technical Notes

Note presenting testing of the gliding of one metal crystal with respect to another, along their mutual grain boundary, during high-temperature creep tests conducted with bicrystals of pure aluminum. Stresses of from 1 to 100 psi and temperatures from 200 to 650 degrees Celsius were employed. Results regarding grain boundary glide rate, influence of orientation difference between grains, influence of temperature, influence of applied stress, structure of the operated grain boundary, and structural changes within grains are provided