Formation of cubic Ll sub 2 phases from Al sub 3 Ti and Al sub 3 Zr by transition metal substitutions for Al

Conference · Mon Jan 01 04:00:00 EST 1990

OSTI ID:6986589

Sparks, C J; Porter, W D; Schneibel, J H; Oliver, W C; Golec, C G

Alloys of (Al{sub x}M{sub 1{minus}x}){sub 3}Ti where M is V, Cr, Mn, Fe, Co, Nb, W, Fe + Ga or Fe + Ga + Mn were fabricated to form the Ll{sub 2} cubic phase, tested for ductility, and characterized by lattice parameter, microstructure, quantitative phase analysis, and phase composition. The elements V, Co, Nb, W, Fe + Ga and Fe + Ga + Mn are hereby newly found Ll{sub 2} formers in Al{sub 3}Ti. Both x-ray diffraction and microprobe analysis were used to identify the phases, their volume fractions and compositions. The amount of ternary addition found in the Ll{sub 2} cubic phase varied between 4 and 12 atomic percent. This amount of ternary addition decreased as the atomic radius of the elemental addition increased. Pettifor's Mendeleev number was a useful guide in the selection of elements to form the Ll{sub 2} phase but did not correlate strongly with the amount of the ternary addition. For the DO{sub 23} phase of Al{sub 3}Zr, the elements V, Mn, and Co were added to the list of Ni, Cu, Fe, and Cr as elements known to form the Ll{sub 2} phase. Little if any ductility was observed in these cubic Ll{sub 2} phases which readily cleaved with transgranular failure. To achieve ductility and toughness, more than transformation of these compositions from a lower to a higher symmetry crystal structure will be required. 15 refs., 3 figs., 2 tabs.

• Research Organization: Oak Ridge National Lab., TN (USA)
• Sponsoring Organization: DOE/ER
• DOE Contract Number: AC05-84OR21400
• OSTI ID: 6986589
• Report Number(s): CONF-900466-67; ON: DE90012288
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM BASE ALLOYS
COHERENT SCATTERING
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DIFFRACTION
DUCTILITY
INTERMETALLIC COMPOUNDS
MECHANICAL PROPERTIES
PHASE STUDIES
SAMPLE PREPARATION
SCATTERING
TENSILE PROPERTIES
TITANIUM ALLOYS
TRANSITION ELEMENT ALLOYS
X-RAY DIFFRACTION
ZIRCONIUM ALLOYS