The effect of scandium on the crystal structure of Ti[sub 3]Al

Journal Article · Sun Nov 15 04:00:00 EST 1992 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(92)90086-T· OSTI ID:7002092

Munroe, P R ^[1]

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1. Physical Sciences Electron Microscope Unit, Univ., of New South Wales, P.O. Box 1, Kensington NSW 2033 (Australia)

Ti[sub 3]Al has a low density and good oxidation resistance and is envisaged as a candidate material for aerospace applications. However, it exhibits poor ductility and fracture toughness at room temperature, and this has inhibited its commercial exploitation. Much of the research performed on this compound has focussed upon additions of strong [beta]-stabilizers, such as niobium and molybdenum, to Ti[sub 3]Al. These alloys can be heat treated to produce two-phase, ordered hexagonal plus body-centered cubic ([alpha][sub 2]+[beta]), microstructures. Improvements in ductility arise through the ductile [beta] phase inhibiting crack propagation. The purpose of this paper is to improve the ductility of Ti[sub 3]Al, not through alloying and thermomechanical treatments to produce a two-phase microstructure, but by alloying to change the crystal structure of Ti[sub 3]Al from an ordered hexagonal (DO[sub 19]) structure to a higher symmetry ordered face-centered cubic (Ll[sub 2]) structure. It has been shown that the DO[sub 19]-structured compound Co[sub 3]V can be transformed to a Ll[sub 2] structure by additions of iron, with significant improvements in ductility. Furthermore, Al[sub 3]Ti, which has a tetragonal (DO[sub 22]) structure, can be transformed to a Ll[sub 2] structure through additions of transition metal s and other elements.

• OSTI ID: 7002092
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 27:10; ISSN SCRMEX; ISSN 0956-716X
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360102* -- Metals & Alloys-- Structure & Phase Studies
360103 -- Metals & Alloys-- Mechanical Properties
360104 -- Metals & Alloys-- Physical Properties
360105 -- Metals & Alloys-- Corrosion & Erosion
AEROSPACE INDUSTRY
ALLOYS
ALUMINIUM ALLOYS
BCC LATTICES
CHEMICAL COMPOSITION
CORROSION RESISTANCE
CRYSTAL LATTICES
CRYSTAL STRUCTURE
CUBIC LATTICES
DENSITY
DUCTILITY
FABRICATION
FCC LATTICES
HEAT RESISTANT MATERIALS
HEAT RESISTING ALLOYS
HEAT TREATMENTS
HEXAGONAL LATTICES
INDUSTRY
MATERIALS
MATERIALS TESTING
MATERIALS WORKING
MECHANICAL PROPERTIES
MOLYBDENUM ADDITIONS
MOLYBDENUM ALLOYS
NIOBIUM ADDITIONS
NIOBIUM ALLOYS
PHASE STABILITY
PHASE TRANSFORMATIONS
PHYSICAL PROPERTIES
SCANDIUM ADDITIONS
SCANDIUM ALLOYS
STABILITY
TENSILE PROPERTIES
TESTING
THERMOMECHANICAL TREATMENTS
TITANIUM ALLOYS
TITANIUM BASE ALLOYS