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Stabilizing nanoprecipitates in Al-Cu alloys for creep resistance at 300°C

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journal contribution
posted on 2018-11-20, 03:45 authored by Y. H. Gao, C. Yang, J. Y. Zhang, L. F. Cao, G. Liu, J. Sun, E. Ma

Commercial precipitation-hardened Al-Cu alloys are normally used at temperatures below its ageing temperature of ∼225°C, to avoid thermally induced precipitate coarsening and resultant softening. Making such popular Al alloys creep resistant at or above 300°C is thus challenging. Here we present a modified precipitation protocol, exploiting Sc-microalloying and a carefully designed three-step heat treatment to enhance Sc segregation at the matrix/θ′-Al2Cu precipitate interfaces. The stabilized nanoprecipitates enable an order-of-magnitude reduction in creep rate at 300°C, demonstrating the room for microstructure improvement and the potential for property elevation in traditional engineering alloys through innovative processing coupled with synergetic alloying elements.

A carefully designed precipitation protocol produces stable nanoprecipitates in Sc-microalloyed Al-Cu alloys, rendering an order-of-magnitude elevation of creep resistance at 300°C.

Funding

This work was supported by the National Natural Science Foundation of China [Grant Numbers. 51621063, 51625103, 51722104, and 51790482], and the 111 Project of China [Grant Number BP2018008]. E.M. acknowledges support from U.S. DoE-BES-DMSE under [Contract No. DE-FG02-16ER46056]. L.F.C. thanks the financial support by the National Natural Science Foundation of China [Grant No. 51871033] and the National Key Research and Development Program of China [Grant Number 2016YFB0700403].

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