Interstitial impurity interactions and dislocation microdynamics in Mo crystals

Thesis/Dissertation · Thu May 01 04:00:00 EDT 1975

DOI:https://doi.org/10.2172/4197705· OSTI ID:4197705

Kwok, Dora Ng ^[1]

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1. Stony Brook Univ., NY (United States)

The effects of interstitial impurities on the mechanical properties of molybdenum are explored by comparing results obtained for crystals of various interstitial contents controlled by ultra-high vacuum outgassing. Results show a modulus reduction for as-grown samples and for outgassed specimens at low applied stresses. As a function of plastic microstrain, the values of modulus defect for both as-grown and outgassed specimens saturate at the same value. Interstitial impurities act as pinning agents to dislocation bowing, but when all the easy dislocation loops have broken away from local interstitial pins, the modulus defect reaches a constant saturation value. Etch pitting techniques were used to correlate microstrain observations with dislocation generation and motion. It has been found that edge dislocation generation and movement are active in the microstrain region while screw dislocations are relatively inactive until the macrostrain region is reached. Dislocation velocities range from 10^-6 to 10^-3 cm/s and the average distance between interstitial impurity pinning points is found to be approximately 8 x 10^-4 cm.

• Research Organization: Stony Brook Univ., NY (United States)
• Sponsoring Organization: US Energy Research and Development Administration (ERDA)
• NSA Number: NSA-32-020306
• OSTI ID: 4197705
• Report Number(s): COO--3476-11
• Country of Publication: United States
• Language: English

Related Subjects

*MOLYBDENUM-- MECHANICAL PROPERTIES
36 MATERIALS SCIENCE
DEGASSING
DISLOCATIONS
ETCHING
IMPURITIES
INTERSTITIALS
MAGNETIC FLUX
N50230* --Metals
Ceramics
& Other Materials--Metals & Alloys--Properties
Structure & Phase Studies
STRAINS
STRESSES
ULTRAHIGH VACUUM