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Title: Comparative evaluation of cast aluminum alloys for automotive cylinder heads: Part I Microstructure evolution

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''θ'' in Al-Cu alloy, θ'θ' in Al-Si-Cu alloy, and β'β' in Al-Si alloys) with varying size, morphology, coherency, and thermal stability.
Authors:
 [1] ;  [2] ;  [3] ;  [2] ;  [2]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Indian Inst. of Technology (IIT), Kharagpur (India)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
  3. Nemak, Garza Garcia, N.L. (Mexico)
Publication Date:
Grant/Contract Number:
AC05-00OR22725
Type:
Accepted Manuscript
Journal Name:
Metallurgical and Materials Transactions. A, Physical Metallurgy and Materials Science
Additional Journal Information:
Journal Volume: 48; Journal Issue: 5; Journal ID: ISSN 1073-5623
Publisher:
ASM International
Research Org:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org:
USDOE
Country of Publication:
United States
Language:
English
Subject:
36 MATERIALS SCIENCE
OSTI Identifier:
1360030