A high temperature nanoindentation study of Al–Cu wrought alloy

Abstract

a b s t r a c tAluminum-copper alloys are widely used because of their low density and good mechanical strength accomplished with precipitation hardening. The alloy Al-Cu-Mg-Pb (AA2030) has been investigated before and after aging, at room temperature and at high temperatures. The mechanical properties at room temperature have been studied by Brinell hardness tests. T4 and T6 stages of the alloy have been investigated by differential scanning calorimetry up to 450°C, showing the precipitation of different clusters. High temperature nanoindentation has been used to characterize the mechanical properties up to 460°C in order to obtain a better understanding of the local dominating deformation mechanism in the material. A continuous decrease in the hardness and Young's modulus was found with the increasing temperature. The strain rate sensitivity of the alloy increased with the temperature from 0.022 at RT, up to 0.16 at 460°C. The activation volume was constant (around 31-41 b 3 ) up to 240°C, beyond this point a large increase was observed up to 178 b 3 . The results were comparable with similar materials, and indicate thermally activated processes.

Temperature-dependent nanoindentation response of materials

“…[94] AA2030 Decrease of hardness and Young's modulus, and increase of SRS and activation volume with increasing temperature. [95] SAC305 Independence of Young's modulus of the eutectic phase to temperature; Larger creep deformation of the Sn-rich phase than that of eutectic phase; Greater SRS of eutectic phase at the temperature regime of 25-130°C attributable to the mismatch between the β-Sn and intermetallic compound components in the eutectic microstructure. [96] PA6 No close correlation between the tensile and nanoindentation modulus at high temperatures, attributable to the shift in the T g of PA6 owing to the hydrostatic stress imposed by the indenter.…”

Structure and growth of core–shell nanoprecipitates in Al–Er–Sc–Zr–V–Si high-temperature alloys

“…The thermogram displays two prominent exothermic peaks at 90 and 300 ⁰C, which may be attributed to GP-zone formation and subsequent nucleation of Al3Er nanoprecipitates, respectively, due to high diffusivity of the Er. Peaks involving GP and Guinier-Preston-Bagaryatsky's (GPB) zones generally appear at ~ 100 ⁰C in precipitation-hardenable Albased alloys [31,32]. Koch et al [32] report the formation of GPB zones in Al-Cu-Mg-Pb at ~ 80 ⁰C with a T4 heat treatment and at ~ 100 ⁰C with a T6 heat treatment.…”

“…Peaks involving GP and Guinier-Preston-Bagaryatsky's (GPB) zones generally appear at ~ 100 ⁰C in precipitation-hardenable Albased alloys [31,32]. Koch et al [32] report the formation of GPB zones in Al-Cu-Mg-Pb at ~ 80 ⁰C with a T4 heat treatment and at ~ 100 ⁰C with a T6 heat treatment. Similarly, Smith [33] demonstrated the formation of GP-zones at 110 ⁰C during DSC analyses of a solution heat-treated 2124 aluminum alloy.…”

Hardness-Depth Relationship with Temperature Effect for Single Crystals—A Theoretical Analysis

“…So far, plenty of experimental works have been performed in the field of high temperature nano-indentation [5][6][7][8][9][10], and some principal features observed in these experiments indicate that the well-known indentation size effect, that is, the increase of materials hardness with decreasing indentation depth, still exists even when the testing temperature T increases up to T m /3 (T m is the melting temperature) for most materials [11][12][13][14][15]. However, when compared with the test performed at room temperature, both the increasing rate of materials hardness and ultimate bulk hardness are noticed to get weakened at elevated temperatures [9,15].…”