Exploratory alloy development in the system Al-Sc-X

Technical Report · Tue Nov 01 00:00:00 EST 1988

OSTI ID:6759874

Sawtell, R R

The goal of this work has been to improve the cost/performance balance in Al-Sc-X alloys by optimizing the precipitation hardening component of strengthening in these alloys. The approach involved selecting ternary additions that would interact with Sc in the L1/sub 2/ phase precipitates known to form in Al-Sc alloys, modifying the precipitates and increasing overall precipitate volume fraction. The rare earth (RE) elements were chosen as candidates because of their chemical similarity to Sc. Stabilities of various phases in the Al-RE and Al-Sc-RE systems were considered with emphasis on conditions favorable to formation of the L1/sub 2/Al/sub 3/(Sc,RE) phase. The thermodynamics of precipitation of this phase in an Al matrix was then considered. Having established the likelihood of interaction of various RE in L1/sub 2/ precipitates attention was turned to effects of these variations in precipitate character on relative strengthening efficiency. The precipitates become more effective obstacles as size of the RE addition increases. An experimental program was developed to investigate effects of RE size at a constant level of alloying on the trade-off between effects of greater precipitate strengthening efficiency provided by larger RE and the accompanying reduction in degree of substitution and, thus, volume fraction. 58 refs., 46 figs., 23 tabs.

• Research Organization: Lawrence Berkeley Lab., CA (USA)
• DOE Contract Number: AC03-76SF00098
• OSTI ID: 6759874
• Report Number(s): LBL-26283; ON: DE89007088
• Resource Relation: Other Information: Thesis (Ph.D.). Portions of this document are illegible in microfiche products
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM BASE ALLOYS
MECHANICAL PROPERTIES
METALLURGICAL EFFECTS
AGING
CHEMICAL COMPOSITION
COLD WORKING
DIFFRACTION
ELECTRIC CONDUCTIVITY
ERBIUM ADDITIONS
GADOLINIUM ADDITIONS
HOLMIUM ADDITIONS
MICROSTRUCTURE
PHASE DIAGRAMS
PHASE TRANSFORMATIONS
PRECIPITATION HARDENING
ROLLING
SCANDIUM ADDITIONS
TENSILE PROPERTIES
THERMODYNAMICS
YTTRIUM ADDITIONS
ALLOYS
ALUMINIUM ALLOYS
COHERENT SCATTERING
CRYSTAL STRUCTURE
DIAGRAMS
ELECTRICAL PROPERTIES
ERBIUM ALLOYS
FABRICATION
GADOLINIUM ALLOYS
HARDENING
HOLMIUM ALLOYS
MATERIALS WORKING
PHYSICAL PROPERTIES
RARE EARTH ADDITIONS
RARE EARTH ALLOYS
SCANDIUM ALLOYS
SCATTERING
YTTRIUM ALLOYS
360103* - Metals & Alloys- Mechanical Properties
360102 - Metals & Alloys- Structure & Phase Studies