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Mechanisms for stabilizing θ'(Al2Cu) precipitates at elevated temperatures investigated with phase field modeling

Journal Article · · Materialia
 [1];  [1];  [2];  [2];  [2];  [1]
  1. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Univ. of Tennessee, Knoxville, TN (United States)
  2. Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
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While most Al–Cu and Al–Si–Cu alloys strengthened by the metastable θ' phase exhibit extensive microstructural degradation above 200 °C, recent experimental work has demonstrated that θ' precipitates can be stabilized to 350 °C by microalloying additions of Mn and Zr, resulting in improved mechanical properties at elevated temperatures. Here, the present work utilizes phase field modeling to study the relationship between microalloying solute elements and the coarsening resistance of θ'. Simulations are designed to parse out the relative influence of various stabilization mechanisms on microstructural evolution of θ' precipitates at elevated temperatures. Specifically, a ternary alloying element is added to a virtual microstructure to study the operation and effectiveness of stabilization mechanisms including solute drag, diffusion barriers, interfacial energy reduction, and lattice strain modification. Simulation results are compared with atom probe tomography observations. Lastly, the simulations rationalize experimental observations of microstructural evolution and solute segregation in Al–Cu–Mn–Zr alloys, and reveal the interlinked thermodynamic and kinetic mechanisms that determine the elevated temperature stability of θ' precipitates.

Research Organization:
Oak Ridge National Laboratory (ORNL), Oak Ridge, TN (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Vehicle Technologies Office (EE-3V); USDOE Office of Science (SC), Basic Energy Sciences (BES) (SC-22). Materials Sciences & Engineering Division
Grant/Contract Number:
AC05-00OR22725
OSTI ID:
1558547
Alternate ID(s):
OSTI ID: 1637252
Journal Information:
Materialia, Journal Name: Materialia Journal Issue: C Vol. 6; ISSN 2589-1529
Publisher:
ElsevierCopyright Statement
Country of Publication:
United States
Language:
English

Figures / Tables (10)

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Table 1 : Part 1(p. 43)table Table 1 : Part 1
Table 1 : Part 2(p. 45)table Table 1 : Part 2
Table 2(p. 46)table Table 2

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Related Subjects

36 MATERIALS SCIENCE
Al–Cu alloys
Atom probe tomography (APT)
Coarsening
Phase-field simulation
θ′-Al2Cu