Phase-Field Simulation of Orowan Strengthening by Coherent Precipitate Plates in an Aluminum Alloy
- 736 Downloads
The density-functional theory and phase-field dislocation model have been used to compute and simulate the strength of θ′ plates and precipitate-dislocation interactions in an Al-4Cu-0.05Sn (wt pct) alloy that is strengthened exclusively by coherent θ′ precipitate plates. The density-functional theory computation indicates that a 1.06 GPa applied stress is required for a dislocation to shear through a θ′ plate, which is far larger than the critical resolved shear stress increment (ΔCRSS) of the peak-aged sample of the alloy. The ΔCRSS values of the alloy aged for 0.5, 3, 48, and 168 hours at 473 K (200 °C) are computed by the phase-field dislocation model, and they agree well with experimental data. The phase-field simulations suggest that the ΔCRSS value increases with an increase in plate aspect ratio and number density, and that the change of ΔCRSS is not sensitive to the variation of the distribution of θ′ plate diameters when the average diameter of θ′ plates is fixed, and that the coherency strain of θ′ plates does not contribute much to ΔCRSS of the alloy when the θ′ number density and aspect ratio are below certain values. The simulations further suggest that, when the volume fraction of θ′ is constant, the ΔCRSS value for a random spatial distribution of the θ′ plates is 0.78 times of that for a regular spatial distribution.
KeywordsBurger Vector Slip Plane Habit Plane Elastic Strain Energy Coherency Strain
The authors are grateful to the support from the Australian Research Council. Y.W. also acknowledges the support from the ARC International Fellowship. H.L. wishes to acknowledge the support from Monash University in the form of Monash Graduate Scholarship and International Postgraduate Research Scholarship. Y.G. and Y.W. acknowledge the financial support from US Department of Energy, Office of Basic Energy Sciences under grant DE-SC0001258 and the National Science Foundation under NSF DMREF Program, Grant No. DMR-1435483.
- 1.I. J. Polmear: Light Alloys: Metallurgy of the Light Metals, 3rd ed. Arnold, London, 1995.Google Scholar
- 2.B. C. Muddle, S. P. Ringer, and I. J. Polmear: Trans. Mater. Res. Soc. Jpn., 1994; vol. 19B, pp. 999.Google Scholar
- 6.J.R. Pickens, H.F. Heubaum, T.J. Langan, and L.A. Kramer: Proc. of the 5th Int. Conf. on Aluminum-Lithium Alloys, vol. 1989, E.A. Starke, T.H. Sanders, eds., Mater. and Comp. Eng. Publications, Birmingham, p. 1397.Google Scholar
- 15.J. M. Slicock, T. J. Heal, and H. K. Hardy: J. Inst. Metals, 1953, vol. 82, pp. 239-45.Google Scholar
- 19.P.B. Hirsch and F.J. Humphreys: The Physics of Strength and Plasticity, A.S. Argon, ed., MIT Press, Cambridge (MA), 1969.Google Scholar
- 22.M. F. Ashby: Acta Metall., 1966; vol. 14, pp. 678-81.Google Scholar
- 23.L.M. Brown and R.K. Ham: Strengthening Methods in Crystals. Applied Science Publishers, London, 1971.Google Scholar
- 24.M.F. Ashby: in The Physics of Strength and Plasticity, A.S. Argon, ed. MIT Press, Cambridge (MA),1969, pp. 143–58.Google Scholar
- 31.R. L. Fullman: Trans. AIME 1953; vol. 197, pp. 447-52.Google Scholar
- 39.S. Koda and K. Matsuura: J. Inst. of Metals 1963; vol. 91, pp. 229-36.Google Scholar
- 41.A. G. Khachaturyan: Theory of Structural Transformations in Solids. New York: John Wiley & Sons; 1983.Google Scholar