Methods of investigating the corrosion-fatigue strength and stress-corrosion cracking of materials at high temperatures and pressures

New methods of investigating the corrosion-fatigue strength and stress-corrosion cracking of materials at elevated temperatures and pressures are described.     

Method of investigating the moisture content of outside walls

A method is described for determining the moisture content of outside walls using gamma-ray irradiation by layers.     

Premelting of iron at high pressures under conditions of contact with amorphous argon

Experiments involving shock-wave loading systematically produce higher melting temperatures than those obtained in experiments involving the use of diamond anvils (DAC). The melting temperature in DAC experiments is determined by structural changes on the surface of a solid in contact with another substance (for example, with argon). We use the method of molecular dynamics to investigate the process of iron melting from the surface in single-component and two-component (in the presence of argon as medium) cases at pressures of ～100 GPa. In the argon-iron two-component model aimed at reproducing the conditions of static DAC measurements, premelting is observed at a temperature below T _m . The layer of iron adjacent to argon may make a transition to disordered state under certain conditions. The temperature interval at constant pressure, in which this effect is observed, is comparable in magnitude with the difference between the melting temperatures obtained as a result of dynamic and static measurements. Therefore, this effect may be one of the reasons for discrepancy between the experimental results for the melting curve of iron and other metals.     

Dislocations produced in magnesium oxide crystals due to contact pressures developed by softer cones

An experimental investigation shows that dislocations, encompassing a predictable dislocated volume, are produced in MgO single crystals subjected to circular contact pressures due to cones of other solids which may be an order of magnitude softer. The mean contact pressure necessary to produce localized plastic flow, without fracture, is shown to be directly related to the critical resolved shear stress of the MgO. Dislocation etching is used to investigate the influence of cone hardness and normal loading on the nature of the deformed zone in the harder crystal and the results are discussed in terms of the deformation characteristics of the softer cones and the crystal.