Evidence for pre {delta}{prime} precipitation events in an Al-Li alloy

Journal Article · Sat Jul 01 04:00:00 EDT 1995 · Scripta Metallurgica et Materialia

DOI:https://doi.org/10.1016/0956-716X(95)00037-V· OSTI ID:99226

Noble, B; Trowsdale, A J ^[1]

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1. Univ. of Nottingham (United Kingdom). Dept. of Materials Engineering and Materials Design

Differential scanning calorimetry measurement on a quenched A1-4wt%Li alloy show a large exothermic event taking place prior to {delta}{prime} precipitation, and with an activation energy of 54.5kJ mol{sup {minus}1}. This exotherm has been attributed to a combination of ordering and spinodal decomposition into lithium-lean and lithium-rich regions, the diffusion involved being controlled by quenched-in vacancies. The spinodal decomposition process is complete within 10 min. holding at room temperature. The spinodally decomposed alloy evolves into {delta}{prime} particles with an L1{sub 2} ordered structure. The activation energy is lower than that normally observed for the diffusion of lithium in aluminium, and is attributed to excess vacancies assisting {delta}{prime} precipitation.

• OSTI ID: 99226
• Journal Information: Scripta Metallurgica et Materialia, Journal Name: Scripta Metallurgica et Materialia Journal Issue: 1 Vol. 33; ISSN 0956-716X; ISSN SCRMEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ACTIVATION ENERGY
ALUMINIUM BASE ALLOYS
CALORIMETRY
DIFFUSION
LITHIUM ALLOYS
ORDER-DISORDER TRANSFORMATIONS
PARTICULATES
PRECIPITATION
QUENCHING
SOLID SOLUTIONS
VACANCIES