Fracture of a manganese-modified titanium trialuminide alloy

Journal Article · Thu Jul 01 04:00:00 EDT 1993 · Acta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-7151(93)90377-5· OSTI ID:6273039

Morris, D G; Morris, M A; Leboeuf, M ^[1]

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1. Univ. of Neuchatel, Neuchatel (Switzerland). Inst. of Structural Metallurgy

Titanium trialuminides show limited tensile ductility and are known to fail by transgranular cleavage. Examinations of the fracture surfaces of a manganese-modified version of Al[sub 3]Ti with L1[sub 2] crystal structure shows that fracture normally begins at the outside surface of a sample by intergranular failure and only later becomes transgranular. This is interpreted as an environmental influence weakening grain boundaries and initiating cracking. Cleavage cracks propagate subsequently through the grains with limited dislocation emission leading to only minor stress relaxation. The dislocations produced are APB-dissociated super-dislocations which are mobile in the lattice. The limited extent of crack stress relaxation appears to be due to difficulties of operating dislocation sources. Two hypotheses may be suggested to explain this: the extent of dissociation of the superdislocation partials is insufficient for the individual dislocations to behave independently and the superdislocation behaves as a single dislocation of large Burgers vector; the core structure of each superpartial is insufficiently dissociated to allow easy emission of elementary Shockley partial dislocations. The low ductility of the material may also be related to the very low density of mobile dislocations in the initial material.

• OSTI ID: 6273039
• Journal Information: Acta Metallurgica et Materialia; (United States), Journal Name: Acta Metallurgica et Materialia; (United States) Vol. 41:7; ISSN 0956-7151; ISSN AMATEB
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360103* -- Metals & Alloys-- Mechanical Properties
ALLOYS
ALUMINIUM ALLOYS
CLEAVAGE
COHERENT SCATTERING
CRACK PROPAGATION
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DIFFRACTION
DISLOCATIONS
DUCTILITY
EXPERIMENTAL DATA
FAILURES
FRACTURES
GRAIN BOUNDARIES
INFORMATION
INTERMETALLIC COMPOUNDS
LINE DEFECTS
MANGANESE ALLOYS
MECHANICAL PROPERTIES
MICROSCOPY
MICROSTRUCTURE
MORPHOLOGY
NUMERICAL DATA
RELAXATION
SCATTERING
STRESS RELAXATION
TENSILE PROPERTIES
TITANIUM ALLOYS
X-RAY DIFFRACTION