Precipitation Behavior of the Metastable Quasicrystalline I-Phase and θ′-Phase in Al-Cu-Mn Alloy

Abstract

The precipitation behavior and mechanical properties for conventionally solidified Al-2.0wt.%Cu-2.0wt.%Mn alloy were studied. The supersaturated aluminum-based solid solution, CuAl2, Al6Mn and Al20Cu2Mn3 phases of solidification origin were identified after casting. The high temperature ageing of as-cast samples (T5 treatment) in a temperature range of 300–350 °C led to the formation of the metastable θ′ phase and equiaxed precipitates of the quasicrystalline-structured I-phase. The θ′ phase demonstrated a high size stability in a studied temperature range with a mean length of ~300 nm and a mean thickness of ~24 nm. A mean size of the I-phase precipitates varied in a range of ~30–50 nm depending on the treatment regimes. The rod-shaped T-phase precipitates were formed with an increase in ageing temperature to 400 °C. Mechanical properties were analyzed at room temperature in a solid solution-treated state. The increased yield strength at room temperature and 200–300 °C were observed after ageing at 300 °C for 148 h.

The Microstructure and Properties of Al–Mn–Cu–Zr Alloy after High-Energy Ball Milling and Hot-Press Sintering

“…The low-temperature effect can also be the result of the θ-phase (CuAl 2 ) precipitation that was observed by XRD for the alloy annealed at 350-450 • C for 2-4 h. The P1 peak was non-symmetric with two maxima, so both phenomena were possible. The P2 effect was the result of Mn-bearing phases that can precipitate at temperatures of 300-350 • C [103][104][105][106][107]. The P3 effect with the maximum at ~430 • C can be explained by the precipitation of the Al 3 Zr phase, which is in good agreement with several studies showing that L1 2 -Al 3 Zr phase precipitates predominantly at 350-450 • C [37].…”

“…The chemical composition of the alloy indicates the existence of three equilibrium phases Al6Mn, Al20Cu2Mn3, and Al3Zr (D023) in the studied temperature range. The formation of the Al3Zr (L12) and CuAl2 phases is also reasonable at the temperatures studied [35,103,104]. The Al6Mn, CuAl2, Al3Zr (L12), and Al20Cu2Mn3 phases were revealed by XRD after annealing in the studied temperature range of 350-450 °C for 2-4 h. During hot pressing, the maximum time at elevated temperature was ~15 min.…”

“…The chemical composition of the alloy indicates the existence of three equilibrium phases Al 6 Mn, Al 20 Cu 2 Mn 3 , and Al 3 Zr (D0 23 ) in the studied temperature range. The formation of the Al 3 Zr (L1 2 ) and CuAl 2 phases is also reasonable at the temperatures studied [35,103,104]. were completely dissolved and only 5.1 wt% (2.7 at%) Mn was present in the solid solution.…”

Effect of Fe-Bearing Phases on the Mechanical Properties and Fracture Mechanism of Al–2wt.%Cu–1.5wt.%Mn (Mg,Zn) Non-Heat Treatable Sheet Alloy

“…In the presence of 1% Mg and 1% Zn, the Mg 2 Si and Al 2 CuMg (S) phases were added to the above-mentioned ones. All these phases can be present in graded aluminum alloys and have been studied quite well [46][47][48][49][50][51][52][53][54].…”

“…In the presence of 1% Mg and 1% Zn, the Mg2Si and Al2CuMg (S) phases were added to the above-mentioned ones. All these phases can be present in graded aluminum alloys and have been studied quite well [46][47][48][49][50][51][52][53][54]. The analysis of the microstructure of the ingots (10F) focused on the morphology of the excess phases (Figure 2), their identification (Table 3), and the determination of the aluminum solid solution composition (Table 4).…”