Dissociated matrix dislocations in a omicron/omicron'Ni-based single crystal superalloy

Journal Article · Mon Oct 01 04:00:00 EDT 1984 · Scr. Metall.; (United States)

DOI:https://doi.org/10.1016/0036-9748(84)90200-X· OSTI ID:5897605

Decamps, B; Caron, P; Condat, M; Khan, T

The fine dispersion of ordered (Ll/sub 2/)omicron' precipitates whose composition is based on Ni/sub 3/Al is the principal source of strengthening in nickel-based superalloys at high temperatures. In alloys which contain high volume fraction of omicron', the creep deformation occurs partly by shear of the precipitates. A recent investigation of Caron and Khan on a single crystal superalloy designated CMSX-2 confirmed the previous findings of Leverant and Kear and Leverant et al. on MAR-M200 that the shearing process of omicron' precipitates during creep is temperature dependent. During primary creep at intermediate temperatures (T = 760/sup 0/C) the shearing of the precipitates occurs by (111)<112> slip with the creation of both intrinsic and extrinsic stacking faults within the precipitates. At temperatures above 850/sup 0/C, shearing of the omicron' particles occurs exclusively by pairs of a/2<110> dislocations coupled by high energy APB. It has previously been suggested by Leverant et al. that the matrix stacking fault energy (SFE) should play an important role in determining the type of shearing process in omicron/omicron' superalloys. The purpose of this paper is to present an experimental evidence of dislocation dissociation in the matrix of a omicron/omicron' single crystal superalloy derived from CMSX-2, during the early stages of creep deformation at 900/sup 0/C. The local aspect of matrix dislocations is described and some consequences on the subsequent shearing process are proposed.

• Research Organization: Office National d'Etudes et de Recherches Aerospatiales, Chatillon
• OSTI ID: 5897605
• Journal Information: Scr. Metall.; (United States), Journal Name: Scr. Metall.; (United States) Vol. 18:10; ISSN SCRMB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals &amp; Alloys-- Structure &amp; Phase Studies
ALLOYS
ALUMINIUM ALLOYS
CREEP
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
CRYSTALS
DISLOCATIONS
DISSOCIATION
HARDENING
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
LINE DEFECTS
MATERIALS
MATRICES
MECHANICAL PROPERTIES
METALLURGY
MONOCRYSTALS
NICKEL ALLOYS
NICKEL BASE ALLOYS
PHYSICAL METALLURGY
SHEAR