DIFFUSIONLESS PHASE CHANGES IN NON-FERROUS METALS AND ALLOYS. Technical Progress Report for Period April 1, 1958-April 30, 1959
The motion of twin boundaries in the absence of plastic deformation and accomodation lunking were studied in beta phase Au-- Cd alloys. Crystals were grown from pure elements and prepared by grinding, and electrolytic polishing and etching. A proposed mechanism for twin boundary motion based on experimental results is presented. Aspects of this mechanism become apparent in the conclusions that nucleation of twinning dislocations under the applied stress requires thermal activation energy of <0.1 ev. Twin boundury motion occurs by nucleation of twinning dislocations adjacent to the existing twin interfaces and spreading of these loops by applied stress; new twin orientations also occur by this mechanism. The restoring force on the displaced bounduries results from increase in internal energy of the volume of the crystal through which the boundaries were displaced. Order faults in the crystals provide an effective barrier to the motion of the twinning dislocations through the lattice. Quenching effects in beta phase goldzinc were investigated by studying the effects of quenching temperatures on the concentration of defects, and determination of the activation energy of formation. It was found that defects are thermally activated, and motions of the defects to sinks are also thermally activated. Relaxation around a vacancy is probably the cause of a discrepancy between results obtained from crystals resistivity measurements and volume change measurements. Results of a study to measure the kinetics of isothermal transformations and to compare isothermal and athermal transformations in annealed slow cooled 49 at. % Cd--Au alloys are reported. Mechanisms found in these transformations include isothermal growth of embryos with subsequent formation of dartensitic plates, and movement of interfaces through large volumes of the crystal. (J.R.D.)
- Research Organization:
- Illinois. Univ., Urbana
- DOE Contract Number:
- AT(11-1)-67
- NSA Number:
- NSA-14-001830
- OSTI ID:
- 4212518
- Report Number(s):
- AECU-4394; MEDUI-5-AEC
- Resource Relation:
- Other Information: Project No. 15. Orig. Receipt Date: 31-DEC-60
- Country of Publication:
- United States
- Language:
- English
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DIFFUSIONLESS PHASE CHANGES IN NON-FERROUS METALS AND ALLOYS. Technical Progress Report for March 1, 1957-March 31, 1958
DIFFUSIONLESS PHASE CHANGES IN NON-FERROUS METALS AND ALLOYS. Technical Progress Report
Related Subjects
ANNEALING- COOLING- DIFFUSION LENGTH- ELECTRIC CONDUCTIVITY- EXPANSION- HEAT TREATMENTS- LATTICES- MARTENSITE- MEASURED VALUES- PLATES- QUANTITY RATIO- RELAXATION- VARIATIONS- VOLUME
CLEANING- CRYSTALLIZATION- CRYSTALS- DEFECTS- DEFORMATION- DIFFUSION- ELECTROLYSIS- ELEMENTS- ETCHING- EXCITATION- GOLD ALLOYS- GRAIN BOUNDARIES- GRINDING- IMPURITIES- MACHINING- MOTION- NUCLEATE BOILING- PHASE DIAGRAMS- REACTION KINETICS- STRESSES- SURFACES- THERMODYNAMICS- VACANCIES