Accession Number : AD0639603

Title :   THE MICROSTRAIN REGION IN HIGH-PURITY REFRACTORY METALS.

Descriptive Note : Quarterly rept. no. 2, 1 Jun-31 Aug 66.

Corporate Author : FRANKLIN INST RESEARCH LABS PHILADELPHIA PA

Personal Author(s) : Prekel,H. L. ; Lawley,A. ; Meakin,J. D.

Report Date : 31 AUG 1966

Pagination or Media Count : 21

Abstract : It is shown that the hydrogen annealing treatmets (described in AD-639 603) which are required in the preparation of molybdenum single crystals suitable for dislocation velocity experiments leave the remaining dislocations in an unpinned state. Some tentative dislocation velocity determinations are presented leading to an activation volum v* approx 20b to the third power in agreement with values of v* = 15b to the third power found by strain-rate change experiments in the macro-strain region. The micro-strain behavior of molybdenum single crystals treated in hydrogen in a similar fasion is examined. The true elastic limit tau sub E. the dissipative friction stress tau sub F, and the activation volume v* are found to be: tau sub E = 0.07 plus or minus 0.0002 Kg/sq, tau sub F = 0.04 plus or minus Kg/sq mm and v* approx 1700b to the third power. These results are compared to those obtained with as zone-refined crystals. (Author)

Descriptors :   (*REFRACTORY METALS, *STRAIN(MECHANICS)), (*MOLYBDENUM, *CRYSTAL DEFECTS), SINGLE CRYSTALS, METAL CRYSTALS, ANNEALING, MICROSTRUCTURE, ELASTIC PROPERTIES, STRESSES, ZONE MELTING

Subject Categories : Properties of Metals and Alloys
      Crystallography

Distribution Statement : APPROVED FOR PUBLIC RELEASE