The motion of energetic charged particles inside a monocrystalline solid can be strongly influenced by channeling and blocking effects. The present article reviews the theory, the experimental studies, and some of the applications of these effects. The coverage of the published literature extends through June 1973.

Channeling and related effects in the motion of charged particles through crystals

The structure and properties of metal-semiconductor interfaces

The effect of interfaces on mechanical properties is considered. Elastic and plastic compatibilities at boundaries are treated. Specific influences at both low and high temperatures are discussed, with emphasis on dislocation mechanisms and the atomic scale structure of boundaries.

The influence of grain boundaries on mechanical properties

It is proposed that interfacial reaction barriers in binary A/B diffusion couples lead to the absence of phases predicted by the equilibrium phase diagram, provided that the diffusion zones are sufficiently thin (thin‐film case). With increasing thickness of the diffusion zones the influence of interfacial reaction barriers decreases and the simultaneous existence of diffusion‐controlled growth of all equilibrium phases is expected (bulk case). Selective growth of the first and second phases and the effect of impurities are discussed with the influence of interfacial reaction barriers and with references to the known cases of silicide formation.

Growth kinetics of planar binary diffusion couples: ’’Thin‐film case’’ versus ’’bulk cases’’

When Hadfield manganese steel in the single-phase austenitic condition was strained in tension, in the temperature range - 25 to 300 °C, it exhibited jerky (serrated) flow, a negative (inverse) strain-rate dependence of flow stress and high work hardening, characteristic of dynamic strain aging. The strain rate-temperature regime of jerky flow was determined and the apparent activation energies for the appearance and disappearance of serrations were found to be 104 kJ/mol and 146 kJ/mol, respectively. The high work hardening cannot be a result of mechanical twinning because at -50 °C numerous twins were produced, but the work hardening was low and no twins were formed above 225 °C even though work hardening was high. The work hardening decreased above 300 °C because of the cessation of dynamic strain aging and increased again above 400 °C because of precipitation of carbides. An apparent activation energy of 138 kJ/mol was measured for static strain aging between 300 and 400 °C, corresponding closely to the activation energies for the disapperance of serrations and for the volume diffusion of carbon in Hadfield steel. Evidence from the present study, together with the known effect of manganese on the activity of carbon in austenite and previous internal friction studies of high-manganese steels, lead to the conclusion that dynamic strain aging, brought about by the reorientation of carbon members of C-Mn couples in the cores of dislocations, is the principal cause of rapid work hardening in Hadfield steel.

Mechanism of Work Hardening in Hadfield Manganese Steel.

The fine structure of (001) twist boundaries in gold was systematically studied by transmission electron microscopy. About 200 such boundaries were prepared under controlled conditions by welding single crystal films together face-to-face at various twist angles Θ. An almost continuous study of the structure was then made over the entire range 0 ⋜ Θ⋜45°. Orthogonal grids of grain boundary misfit screw dislocations were found in the vicinities of critical angles Θc (Θc=0, 22–6, 28.1 and 36.9°). producing various high density coincidence site boundaries. Measured geometrical properties of the grids near each Θc (i.e. grid spacings, orientation and dislocation diffraction contrast) were completely consistent with those predicted for a boundary structure consisting of a suitable misfit dislocation grid embedded in the high density coincidence site interface corresponding to Θc. Fine structure was not detected in appreciable angular ranges lying between the Θc. This may have been due in part to the re...

Quantitative observation of misfit dislocation arrays in low and high angle twist grain boundaries

On measurements of self‐diffusion rates along dislocations in F.C.C. Metals

Special aspects of diffusion in thin films

U.S. Atomic Energy Commission, Contract AT(30-1)-3504.

Additional support was received from the Advanced Research Projects Agency
through the use of the technical facilities of the Materials Science Center at Cornell University.

Annealing Kinetics of Voids and the Self-Diffusion Coefficient in Aluminum

A technique for producing any type of planar dislocation sub-boundary in thin-film bierystal specimens of gold under controlled conditions is described. Single crystal thin films of the desired orientations are first grown epitaxially on appropriate substrates from the vapour phase. Two films, while still on their substrates, are then welded together face-to-face at any desired mis-orientation to produce a thin-film bierystal containing a planar dislocation array at the welded interface. The substrates are then dissolved away to allow examination of the sub-boundary at normal incidence by transmission electron microscopy. The technique is applied to the study of pure twist sub-boundaries on (001) and (111) planes in gold. Features of the structures of these boundaries are described. Further possible applications are discussed.

R. W. Balluffi

Papers

Quantitative observation of misfit dislocation arrays in low and high angle twist grain boundaries

On measurements of self‐diffusion rates along dislocations in F.C.C. Metals

Special aspects of diffusion in thin films

Annealing Kinetics of Voids and the Self-Diffusion Coefficient in Aluminum

Dislocation sub-boundary arrays in oriented thin-film bicrystals of gold