FUNDAMENTALS OF SINGLE CRYSTAL DEFORMATION IN ZONE-REFINED BERYLLIUM. Final Report, July 1, 1961 through June 30, 1962
A study was--made of the fundamental deformation characteristics of beryllium single crystals purified by zone refining. Simgle crystals 1/4 inch and 1 1/4 inches in diameter were prepared by floating zome refining. Mechanical property studies showed that the critical resolved shear stresses at room temperature for basal and prismatic slip decreased in a regular manner with decreasing impurity content, as measured by resistance ratio. Absolute decreases im critical stress were approximately equal for both kinds of slip for equivalent purifications. The lowest values of critical resolved shear stress obtained were 180 psi for basal slip and 7600 psi for prismatic slip. Large increases in basal plane ductility at room temperature, accompanied by decreases in the rate of work hardening, were produced by purification. Extensive ductility was observed in purified crystals at temperatures as low as -- 196 deg C, while at 425 deg C, brittle failure by basal cleavage was elimi-mated. At room temperature, basal slip eventually terminated in basal cleavage for all purities studied. Increases in basal ductility were related to the effect of purification on the split bend- plane model for basal cleavage. These effects involved a reduction im barriers to the motion of individual dislocations and to the motion of bend planes under an applied stress. The role of soluble and insoluble impurities im these processes is discussed. Purification also resulted in elimination of the brittle behavior followimg prismatic slip that is observed in commercial-purity crystals. (auth)
- Research Organization:
- Nuclear Metals, Inc., West Concord, Mass.
- DOE Contract Number:
- AT(30-1)-2784
- NSA Number:
- NSA-17-030976
- OSTI ID:
- 4673592
- Report Number(s):
- NMI-1256
- Resource Relation:
- Other Information: Orig. Receipt Date: 31-DEC-63
- Country of Publication:
- United States
- Language:
- English
Similar Records
EFFECT OF PURIFICATION ON BASAL CLEAVAGE IN BERYLLIUM SINGLE CRYSTALS
PREPARATION AND EVALUATION OF HIGH PURITY BERYLLIUM. Bi-Monthly Progress Report, July 2 to September 1, 1961