Henry Chessin

Relationship between flow stress and atomic order in the FeCo alloy

Abstract Stress–strain curves in compression were obtained as a function of temperature for both the disordered and fully ordered FeCo–B2 type superlattice only. Supplementary observations were made of the surface slip markings after various strains, as well as of the dislocation configurations existing after these strains, using transmission electron microscopy techniques. It has been found that the deformation process occurring in the disordered alloys is similar at all strains. Furthermore, the flow stress is strongly dependent on temperature and nearly independent of strain. The profuse stepped slip lines observed on the surface of these specimens suggests that thermally activated cross-slip is the controlling mode of deformation in the disordered alloys. The ordered alloys, on the other hand, show three distinct deformation stages similar to those observed in face-centred cubic metals and alloys. The flow stress in Stage I is independent of strain. On the other hand, the flow stress in Stage II incre...

Ice nucleation by coprecipitated silver iodide and silver bromide.

The ability of silver iodide to cause freezing of supercooled water is improved if up to 30 percent of the iodine atoms in the crystal are replaced with bromine atoms.

Ice Nucleation by Solid Solutions of Silver-Copper Iodide

The lattice misfit between ice and silver iodide can be reduced by partial substitution of copper atoms for silver atoms in the silver iodide lattice. The best crystal match is obtained with a composition of CuI-3AgI, which corresponds to the most active silver-copper iodide nucleation catalyst.

Ice Nucleation in a Supercooled Cloud by CuI-3AgI and AgI Aerosols

Abstract The relative numbers of active ice nuclei for identically produced aerosols of AgI and CuI-3AgI are determined experimentally. For nuclei activated at temperatures above −9C, CuI-3AgI produces a greater number of active ice nuclei than pure AgI. At temperatures below −9C no measurable difference in nucleation activity can be found.

A Technique for Measuring Relative Threshold Nucleation Temperatures for Active Nucleation Catalysts

Abstract A technique is described for using dilatometers to measure and compare the freezing temperature of water in the presence of various nucleation catalysts. Nucleation is indicated by the increase in volume that water undergone upon freezing.

Ice Nucleation by Miersite

Abstract Miersite, a naturally occurring solid solution of silver iodide and cuprous iodide, can nucleate ice in supercooled water at −1.42C. The excellent ice nucleation properties of miersite can be attributed to the fact that the miersite lattice is only 0.28% larger than the ice lattice.