Next Article in Journal
Fatigue of Thin, Oligo-Crystalline Wires Made of X2 CrNiMo 18-15-3
Previous Article in Journal
Influence of the Velocity and the Number of Polishing Passages on the Roughness of Electrolytic Plasma Polished Pipe Inner Surfaces
Open AccessArticle

Effect of Zr Additions on Thermal Stability of Al-Cu Precipitates in As-Cast and Cold Worked Samples

Materials Science Department, Michigan Technological University, Houghton, MI 49931, USA
Author to whom correspondence should be addressed.
Metals 2018, 8(5), 331;
Received: 9 April 2018 / Revised: 28 April 2018 / Accepted: 1 May 2018 / Published: 8 May 2018
While Zr is frequently added to Al alloys to control grain size with the formation of large (>1 μm) primary precipitates, little research has been conducted on the effect of nanoscale Al3Zr precipitates on Al alloys. By comparing the precipitation and corresponding strength evolution between Al-Cu-Zr alloys with different Zr concentrations, the effects of Zr on Al-Cu precipitation with and without primary Al3Zr precipitates can be observed. In the absence of these large precipitates, all Al3Zr phases can be formed, through high temperature aging treatments, as a dispersion of nanoprecipaites inside the Al grains. In this study, Al-Cu-Zr ternary alloys were produced and heat treated to determine whether an increase in the coarsening resistance of Al-Cu precipitate phases would be observed with a distribution of the more thermally stable Al3Zr nanoprecipitates. Generally, properly aged Al-Cu alloys will coarsen when encountering elevated temperatures higher than ~473 K (~200 °C). Diluted Al-Zr alloys (<0.07 at % Zr) resist coarsening behavior until the significantly higher temperatures of ~673 K (~400 °C), but are comparatively limited in strength because of a limited solubility of Zr in the Al matrix. Hardness testing and transmission electron microscope (TEM) results are discussed, in which it is found that even very small additions of Zr, when properly accounted for during heat treating, produce a finer microstructure and higher strength than in similar Al-Cu binary alloys. No significant change in the thermal stability of strengthening was observed, indicating that the finer precipitate microstructure is resultant from a higher nucleation density, as opposed to a decrease in coarsening behavior. View Full-Text
Keywords: aluminum; zirconium; precipitation strengthening; thermal stability aluminum; zirconium; precipitation strengthening; thermal stability
Show Figures

Figure 1

MDPI and ACS Style

Deane, K.; Sanders, P. Effect of Zr Additions on Thermal Stability of Al-Cu Precipitates in As-Cast and Cold Worked Samples. Metals 2018, 8, 331.

Show more citation formats Show less citations formats
Note that from the first issue of 2016, MDPI journals use article numbers instead of page numbers. See further details here.

Article Access Map by Country/Region

Back to TopTop