Accessible Requires Authentication Published by De Gruyter May 17, 2019

Effects of double-ageing on the mechanical properties and microstructural evolution in the 1460 alloy

Juan Ma, Desheng Yan, Lijian Rong and Yiyi Li

Abstract

The effects of different double ageing processes on the mechanical properties and microstructural evolution in the 1460 alloy were investigated. The corresponding microstructure and mechanical properties of the heat-treated specimens were studied by means of transmission electron microscopy, differential scanning calorimetry, hardness testing and tensile testing. The results show that the elongation of two-step aged (130 °C/84 h + 160 °C/24 h) samples can be increased to 8 % with a minor decrease in tensile strength (450 MPa). Throughout the two-step ageing process, the precipitation behaviour of the alloy exhibited the following characteristics: the δ′ phase formed at lower temperature dissolved into the matrix instead of coarsening and becoming over-aged at the beginning of the second ageing step; finely distributed θ′(Al2Cu) and δ′(Al3Li) at a steady state were obtained, resulting in a significant improvement in tensile strength; and the peak ductility occurred with the precipitation of T1(Al2CuLi) and consumption of δ′(Al3Li), as small δ′ particles caused a co-planar slip, resulting in lower ductility.


Correspondence address, Prof. Dr. L.J. Rong, Division of materials for special environments, Institute of Metal Research, Chinese Academy of Sciences, 72 Wenhua Road, Shenyang 110016, P. R. China, E-mail: , Tel: +86-24-23971979, Fax: +86-24-23978883

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Received: 2018-08-04
Accepted: 2018-11-26
Published Online: 2019-05-17
Published in Print: 2019-05-15

© 2019, Carl Hanser Verlag, München