Internal friction in an aluminium metal matrix composite during thermal cycling

Journal Article · Thu Jul 15 04:00:00 EDT 1993 · Scripta Metallurgica et Materialia; (United States)

DOI:https://doi.org/10.1016/0956-716X(93)90302-9· OSTI ID:6344875

Urreta, S; Schaller, R ^[1]

---

1. Ecole Polytechnique Federale de Lausanne (Switzerland)

The difference in coefficient of thermal expansion (CTE) between reinforcement and matrix in metal matrix composites (MMC) leads to large internal stresses following temperature changes. These stresses may be sufficient to generate plastic flow in the softer matrix phase and lead, in discontinuously reinforced MMC, to a shape change during thermal cycling even in the absence of any applied stress. Dislocation anelasticity and microplasticity in aluminum have been extensively studied by mechanical spectroscopy. In the low and medium stress ranges and for frequencies of about 1 Hz, the internal friction spectrum of aluminum exhibits different maxima between room temperature and 800 K associated to relaxation mechanisms involving volume dislocations. At about 0.4 T[sub M] (T[sub M] = melting point), internal friction peaks arising in thermally activated movement of dislocations are reported. At about 0.6-0.7 T[sub M], internal friction maxima still arise in movement of longer dislocation loops inside the grains, but now activation energies are higher and close to those found for the two regimes of creep in aluminum that is, cross-slip and climb. On the other hand, dislocations arranged in polygonization walls give an internal friction maximum close to T[sub M] at frequencies near 1 Hz. On these bases, mechanical spectroscopy has been employed to investigate the dislocation properties in an aluminum matrix composite, reinforced with short non-oriented alumina fibers, during thermal cycles between 100 K and 800 K.

• OSTI ID: 6344875
• Journal Information: Scripta Metallurgica et Materialia; (United States), Journal Name: Scripta Metallurgica et Materialia; (United States) Vol. 29:2; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602 -- Other Materials-- Structure & Phase Studies
360606* -- Other Materials-- Physical Properties-- (1992-)
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COMPOSITE MATERIALS
CRYSTAL DEFECTS
CRYSTAL STRUCTURE
DATA
DISLOCATIONS
EXPANSION
EXPERIMENTAL DATA
FIBERS
FRICTION
INFORMATION
INTERNAL FRICTION
LINE DEFECTS
MATERIALS
MATRIX MATERIALS
NUMERICAL DATA
OXIDES
OXYGEN COMPOUNDS
TEMPERATURE RANGE
TEMPERATURE RANGE 0065-0273 K
TEMPERATURE RANGE 1000-4000 K
THERMAL CYCLING
THERMAL EXPANSION