Accession Number : AD0720883

Title :   Fundamental Characteristics of Dynamic Slip-Band Propagation.

Descriptive Note : Final technical rept.,

Corporate Author : BATTELLE MEMORIAL INST COLUMBUS OHIO COLUMBUS LABS

Personal Author(s) : Boyd,J. D. ; Hahn,G. T. ; Kanninen,M. F. ; Rosenfield,A. R.

Report Date : 17 MAR 1971

Pagination or Media Count : 8

Abstract : High strain-rate deformation of niobium single crystals is accommodated by a combination of twinning and slip. At a high strain rate more slip systems are activated than at a low rate, and the slip is more homogeneous in character. The edge components of the glide dislocations are more mobile than the screws at a high strain rate, and are rapidly exhausted from the crystal during straining. Neither primary edges or screws react much with secondary dislocations at high strain rates, hence, there is no tendency for dislocations walls to develop during straining. By contrast, at a low strain rate primary dislocations react strongly with secondary dislocations to produce segments of sessile a (001) dislocations. Consequently, a stable array of dislocation walls develop during straining. Subsequent dislocation movement is concentrated in the vicinity of the dislocation walls, and slip becomes markedly non-homogeneous. (Author)

Descriptors :   (*NIOBIUM, DEFORMATION), SINGLE CRYSTALS, DISLOCATIONS, TWINNING(CRYSTALLOGRAPHY), STRAIN(MECHANICS)

Subject Categories : Metallurgy and Metallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE