Estimates Of Density Changes Research Articles

Intermetallic phases in cold-welded AlCu joints

The behaviour of cold-welded AlCu joints during annealing was studied. The deterioration of the cohesion strength of such joints was found to be caused by precipitation of definite intermetallic phases at the interface. Estimates of density changes associated with phase transformation allowed quantitative comparison of the harmfulness of different phases. The present study sets and substantiates the temperature limit of 200°C for the safe exploitation of cold-welded AlCu joints in electrical machines. This is the temperature above which intermetallic phases appear and mechanical properties deteriorate by more than 10% compared with the initial state.

Estimation of density changes associated with growth in vacuum-deposited amorphous films of antimony

Amorphous antimony films consisting of separate islands were deposited onto SiO x and GeO x film substrates at room temperature in a vacuum of 10 -5 Torr. By comparison of the interferometrically determined thickness and the total mass of incident vapour determined with a quartz oscillator, it was found that a sudden change in film density occurs at a certain film thickness d 0. Another change in film density, which is gradual, occurs in the vicinity of a certain thickness d c (d c > d 0 ) . The change at d 0 is caused by the coalescence of neighbouring islands. The change at d c, at which the coalescence of amorphous islands is almost completed, is associated with crystallization.