An Analysis of Strengthening Mechanisms and Rate-Dependence in a High Strength Aluminum Alloy
We examine the strengthening mechanisms within a high-strength aluminum alloy with the objective of providing guidelines for increased strength. First, we measure the mechanical behavior of the age-hardenable Al–Cu–Mg–Ag alloy known as Al 2139 in the T8 condition, and observe strengths of 500 MPa at quasistatic strain rates and average strengths of up to 600 MPa at high strain rates. Next, we explore the reasons for the high strength of this alloy by considering the contributions of various strengthening mechanisms to the total strength of the material. Finally, we develop an analytical approach to estimating the strengthening developed through the mechanism of dislocation cutting of closely spaced plate-like semi-coherent precipitates. Our results suggest that dislocation cutting of the \(\Omega\) phase is the primary strengthening mechanism in this alloy.
KeywordsMechanisms Strength High strain rate Aluminum
The authors acknowledge support from the Army Research Laboratory under ARMAC-RTP Cooperative Agreement number W911NF-06-2-0006. KTR acknowledges support from the Army Research Laboratory through Cooperative Agreement Number W911NF-12-2-0022. We gratefully acknowledge the technical assistance of D. Nguyen with Kolsky bar tests, and of Dr. Kenneth Livi with the STEM.
- 1.Li BQ, Wawner FE (2000) Aluminium alloys: their physical and mechanical properties, pts 1-3. In: Starke EA, Sanders TH, Cassada WA (eds) Aluminium alloys: their physical and mechanical properties, pts 1-3. pp 1359–1364Google Scholar
- 2.Nie JF, Muddle BC, Polmear IJ (1996) Aluminium alloys: their physical and mechanical properties, pts 1-3. In: Driver JH, Dubost B, Durand F, Fougeres R, Guyot P, Sainfort P et al (eds) Aluminium alloys: their physical and mechanical properties, pts 1-3. pp 1257–1262Google Scholar
- 8.Cho A, Bes B (2006) Damage tolerance capability of an Al-Cu-Mg-Ag alloy(2139). In: Poole WJ, Wells MA, Lloyd DJ (eds) Aluminium alloys 2006, pts 1 and 2: research through innovation and technology. pp 603–608Google Scholar
- 11.Casem DT, Dandekar DP (2009) Response of aluminum 2139-T8 to shock loading. In: Elert ML, Buttler WT, Furnish MD, Anderson WW, Proud W G (eds) Shock compression of condensed matter - 2009, pts 1 and 2. pp 973–976Google Scholar
- 15.Casem DT, Dandekar DP (2012) Shock and mechanical response of 2139-T8 aluminum Shock and mechanical response of 2139-T8 aluminum. J Appl Phys. https://doi.org/10.1063/1.3694661
- 16.Ramesh KT (2008) High strain rate and impact experiments. In: Sharpe WN (ed) Springer handbook of experimental solid mechanics. Springer, New York, pp 929–960Google Scholar
- 26.Chester R, Polmear IJ (1983) The metallurgy of light alloys. Institution of Metal-lurgists, LondonGoogle Scholar
- 28.Ardell AJ (1995) Intermetallics as precipitates and dispersoids in high-strength alloys. In: Westbrook JH, Fleischer RL (eds) Intermetallic compounds—principles and practice. Wiley, Chichester, Sussex, pp 257–86Google Scholar
- 29.Li BQ, Wawner FE (1997) Observation of dislocation cutting Omega phase and its strengthening mechanism in an Al-Cu-Mg-Ag alloy. Microsc Microanal 3(2):139–145Google Scholar
- 30.Huang JC, Ardell AJ (1987) Strengthening mechanisms associated with T1 particles in 2 Al-Li-Cu alloys. J Phys 48:373–383Google Scholar
- 31.Argon AS (2008) Strengthening mechanisms in crystal plasticity. Oxford series on materials modeling. Oxford University Press, OxfordGoogle Scholar
- 33.Sun LP (2010) Personal communication: interfacial energiesGoogle Scholar