Precipitation in an Al-3 wt% Cu alloy studied by nuclear magnetic resonance measurements

Author： Yamaguchi S. Wagatuma F. Shinohara T.

ISSN： 1362-3036

Source： Philosophical Magazine Letters, Vol.79, Iss.4, 1999-04, pp. : 171-180

Disclaimer: Any content in publications that violate the sovereignty, the constitution or regulations of the PRC is not accepted or approved by CNPIEC.

Previous Menu Next

Abstract

63Cu nuclear magnetic resonance (NMR) has been applied to a study of the precipitation process in an Al-3 wt% Cu alloy. Structural changes of the precipitate through ageing are reflected in the line shape of the NMR spectra. An intense narrow resonance line appears in the spin-echo spectrum from the solid solution, while the NMR spectrum from the CuAl2 phase of C16-type structure exhibits a characteristic resonance line broadened owing to secondorder quadrupolar effects. The spectra from the Al-3 wt% Cu alloys which contain dispersed precipitates can be fitted by a superposition of the sharp line for the solid solution and a broad line for the precipitate. The breadth of the broad line differs for various precipitates, reflecting the difference in the local environment around the probe atoms. From the intensity ratio of the broad line to the sharp line, the proportion of Cu atoms dissolved in the precipitates is determined. The NMR parameters, such as the Knight shift K and the quadrupolar coupling constant e2qQ/h, are evaluated for the theta and theta precipitates.