A quantitative analysis of strengthening mechanisms and rate-dependence in a high strength aluminum alloy
K.T. Ramesh (Johns Hopkins University), Buyang Cao (), Matthew Shaeffer (Johns Hopkins University)
Prager Medal Symposium in honor of George Weng: Micromechanics, Composites and Multifunctional Materials
Tue 2:40 - 4:00
MacMillan 117
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 550 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, using quantitative TEM together with models for each mechanism. 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, and show that dislocation cutting of the phase is the primary strengthening mechanism in this alloy.