Role of Al[sub 2]O[sub 3] particulate reinforcements on precipitation in 2014 Al-matrix composites

Journal Article · Mon Aug 01 04:00:00 EDT 1994 · Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States)

OSTI ID:6981835

Dutta, I; Dutta, G; Harper, C P ^[1]

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1. Naval Postgraduate School, Monterey, CA (United States)

Precipitation in commercial aluminum alloy 2014, without and with alumina particulate reinforcements, was studied using microhardness, electrical resistivity, differential scanning calorimetry (DSC), and transmission electron microscopy. The precipitation sequence in 2014 Al was confirmed to be [alpha][sub ss] [yields] [alpha] + GPZ [yields] [alpha] + [lambda][prime] [yields] [alpha] + [lambda][prime] + [theta][prime] [yields] [alpha] + [lambda] (AlCuMgSi) + [theta] (CuAl[sub 2]). Reinforcement addition decreased the time to peak hardness, but also reduced the peak matrix microhardness. This was traced to a decrease in the amount of [lambda][prime] formed in the composites. Further, it was observed that while Guinier-Preston (GP) zone and [theta][prime] formations are accelerated in the composites, [lambda][prime] precipitation is decelerated. The acceleration is attributable primarily to enhanced nucleations resulting from an increase in the matrix dislocation density due to coefficient of thermal expansion (CTE) mismatch between the matrix and the reinforcements, whereas the deceleration is associated with a decrease of low-temperature solute diffusivity due to absorption of vacancies at dislocations and interfaces. It was also observed that the degree of overall acceleration in hardening and the reduction in peak matrix microhardness with reinforcement addition decreased with decreasing aging temperatures. The causal relationships of these observations with the associated mechanisms are discussed.

• OSTI ID: 6981835
• Journal Information: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States), Journal Name: Metallurgical Transactions, A (Physical Metallurgy and Materials Science); (United States) Vol. 25:8; ISSN 0360-2133; ISSN MTTABN
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
360602* -- Other Materials-- Structure & Phase Studies
360604 -- Materials-- Corrosion
Erosion
& Degradation
AGING
ALLOYS
ALUMINIUM ALLOYS
ALUMINIUM COMPOUNDS
ALUMINIUM OXIDES
CHALCOGENIDES
COMPOSITE MATERIALS
ELECTRIC CONDUCTIVITY
ELECTRICAL PROPERTIES
HARDENING
MATERIALS
MICROSTRUCTURE
OXIDES
OXYGEN COMPOUNDS
PHYSICAL PROPERTIES
PRECIPITATION
PRECIPITATION HARDENING
REINFORCED MATERIALS
SEPARATION PROCESSES