Abstract
The present study stages a comparative evaluation of microstructure and associated mechanical and thermal response for common cast aluminum alloys that are used for manufacturing automotive cylinder heads. The systems considered are Al-Cu (206-T6), Al-Si-Cu (319-T7), and Al-Si (356-T6, A356-T6, and A356 + 0.5Cu-T6). The focus of the present manuscript is on the evaluation of microstructure at various length scales after aging, while the second manuscript will deal with the mechanical and thermal response of these alloys due to short-term (aging) and long-term (pre-conditioning) heat treatments. At the grain-scale, the Al-Cu alloy possessed an equiaxed microstructure as opposed to the dendritic structure for the Al-Si-Cu or Al-Si alloys which is related to the individual solidification conditions for these alloy systems. The composition and morphology of intermetallic precipitates within the grain and at the grain/dendritic boundary are dictated by the alloy chemistry, solidification, and heat treatment conditions. At the nanoscale, these alloys contain various metastable strengthening precipitates (GPI and θ″ in Al-Cu alloy, θ′ in Al-Si-Cu alloy, and β′ in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.
| Original language | English |
|---|---|
| Pages (from-to) | 2529-2542 |
| Number of pages | 14 |
| Journal | Metallurgical and Materials Transactions A: Physical Metallurgy and Materials Science |
| Volume | 48 |
| Issue number | 5 |
| DOIs | |
| State | Published - May 1 2017 |
Funding
Research sponsored by the Propulsion Materials Program, DOE Office of Vehicle Technologies. This research was performed under a Cooperative Research and Development Agreement (CRADA) between ORNL, Nemak, and FCA US LLC. The authors acknowledge Dongwon Shin (ORNL), Christopher Glaspie (FCA), Gregg Black (FCA), and Seyed Mirmiran (FCA) for reviewing the manuscript. This manuscript has been authored by UT-Battelle, LLC under Contract No. DE-AC05-00OR22725 with the U.S. Department of Energy. The United States Government retains and the publisher, by accepting the article for publication, acknowledges that the United States Government retains a non-exclusive, paid-up, irrevocable, world-wide license to publish or reproduce the published form of this manuscript, or allow others to do so, for United States Government purposes. The Department of Energy will provide public access to these results of federally sponsored research in accordance with the DOE Public Access Plan ( http://energy.gov/downloads/doe-public-access-plan ).