Papers by Keyword: Al-Cu-Mg Alloys

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Authors: M. Yin, D.D. Risanti, Jiang Hua Chen, Sybrand van der Zwaag
Abstract: This work utilizes thermoelectric power (TEP) measurement to track secondary precipitation during the interrupted ageing cycle for AA2024 alloys as well as the subsequent re-ageing cycle. Clear evidences of secondary precipitation were observed which affect the further precipitation sequence during re-ageing. The TEM results confirm that S and S” phases co-exist upon re-ageing.
Authors: Ying Jun Gao, Xian Hua Hou, Chuang Gao Huang
Abstract: Atomic bonding of the GPB zone and S′′ phase of Al-Cu-Mg alloys in early aging stage are calculated using the empirical electron theory (EET) in Solid. The results show that not only the covalence bond-net is very strong in GPB zone, but the whole covalence bond energy of S′′ phase is also very large, all the primary bond-net framework of these precipitates can consolidate the matrix of alloy. Phase transformation from GPB zone to S′′ phase is explained reasonably based on atomic bonding and total binding capacity of Al and Cu atoms in these precipitates.
Authors: Zhi He, Lan Yun Li, Yong Qin Liu
Abstract: This paper investigates a new method, the Levenberg-Marquardt method, to calculate the phase equilibria of the Al-Cu-Mg ternary alloys. The Levenberg-Marquardt method is the best algorithm to obtain the least-square solution of non-linear equations. Its application to ternary Al-Cu-Mg system is executed in detail in this paper. The calculated phase equilibria agrees well with the experimental results. Furthermore, the Levenberg-Marquardt method is not sensitive to the initial values.
Authors: Li Wei Quan, Gang Zhao, Yue Liu, Ni Tian, Tao Peng
Abstract: The precipitates of bending-age-formed ternary Al-4.31Cu-1.51Mg alloy were studied with load of 6.05 kg aged at 190°C. Transmission electron microscopy and electron diffraction has been used to observe the microstructures of the bend-age-formed alloy. The results show that there is no preferential alignment of S phase or GPB zones in the alloys with load compared with that without load. It is interesting to find that the length of S phase is shorter in age-formed sample than that without load. Dislocations generated after loaded can provide enough nucleation sites for the nucleation and growth of S phase.
Authors: Christophe Sigli, Ronan Dif, B. Commet, Timothy Warner
Authors: Zhong Wei Chen, Li Fan, Pei Chen
Abstract: The early age hardening behavior in Al-Cu-Mg alloys with fixed Cu content (0.50 wt%) and varying amounts of Mg has been studied by hardness tests and TEM observation. Two alloys both exhibit the early rapid hardening phenomenon based on large solute-aggregates analysis. Ageing time of early stage rapid hardening of Al-0.5Cu-1.99Mg alloys is less than that of Al-0.5Cu-1.48Mg alloys. For two alloys, ageing time of early stage rapid age hardening reduces with artificial ageing temperature increasing. The early stage rapid age hardening is depended on the composition and artificial ageing temperature. Forming larger solute-aggregates may give rise to early rapid age hardening.
Authors: Ivan Zuiko, Marat Gazizov, Rustam Kaibyshev
Abstract: Microstructure, precipitation behaviour and mechanical properties of an Al-5.64Cu-0.33Mn-0.23Mg-0.14Zr-0.11Ti (in wt. %) alloy subjected to thermomechanical processing (TMP) involving equal-channel angular pressing (ECAP) at ambient temperature to total strains (ε) of ~1 and ~2 followed by aging at 180°C for 0-28 h have been investigated and compared with conventional aging at the same temperature (T6 state). TMP led to significant increase in yield stress (YS) and ultimate tensile strength (UTS) and decrease in elongation-to-fracture as compared to the peak-aged T6 state. The YS, UTS and δ values attained after ECAP to ε ~ 2 followed by peak ageing were ~510 MPa, ~540 MPa and ~7.6%, respectively. The changes in mechanical properties were related to microstructure evolution and precipitation behaviour. TMP conditions obtaining a high-strength state of the Al-Cu-Mg alloy are discussed.
Authors: D.D. Risanti, Sybrand van der Zwaag
Abstract: The anelastic behavior of AA2024 alloy is studied in the temperature range between room temperature and 325 °C. The internal friction technique is shown to be very sensitive to the microstructural changes that take place at these temperatures. Interrupted aging performed at low temperature induces increase in the peak height at ~230 °C indicating the slow release of vacancies aiding the aggregation of Mg and Cu which further transforms into semicoherent precipitates. Stretched specimens indicate increase in background which is attributed to anelastic or viscoelastic of dislocations. TDIF of T6I4 samples is strongly affected to the point of deformation, whilst TDIF of T6I6 samples is affected by the deformation but irrespective to the point of deformation.
Authors: Ivan Zuiko, Vladislav Kulitckii, Rustam Kaibyshev
Abstract: The present study deals with the effect of pre-deformation technique of AA2519 alloy (Al–5.64Cu–0.33Mn–0.23Mg–0.15Zr–0.11Ti–0.09V–0.08Fe–0.01Si (wt. %)) under T8 tempers, on condition that intermediate strains are equal. After undergoing T87 by pre-stretching and peak ageing the alloy demonstrates the yield stress, ultimate tensile strength and elongation to failure of 425.4±2.4 MPa, 475±2.4 MPa, 12.1±0.4%, respectively. The 7% pre-straining by rolling leads to-5% decrease in yield stress, practically the same ultimate tensile strength and-20% decrease in ductility. This effect can be ascribed to more homogeneous distribution of dislocations which act as heterogeneous nucleation sites for the θ′-phase precipitation. In addition to precipitates of the Al–Cu family (θ′′ and θ′), Ω-phase plates on {111}α habit plane was observed. The effect of pre-straining prior to ageing on the precipitation behavior and its relation with mechanical properties of the AA2519 is considered.
Authors: Bao Lin Wu, Gui Ying Sha, Yi Nong Wang, Yu Dong Zhang, Claude Esling
Abstract: Heavy deformation plus micro alloying could be an effective way to obtain ultrafine grain structure of metals. In the present work, an Al-Cu-Mg alloy was microalloyed with Zr to obtain homogeneous precipitates and then heavily deformed by conventional forging at high temperature. The possible refining processing routes were studied and the superplasticity behaviors of the alloy was investigated. Results show that the micro alloyed alloy can be stably refined to 3-5μm under conventional processing routes. The Al-3Zr precipitates act both as additional sites to enhance recrystallization nucleation rate and pins to impede grain growth to increase the thermal stability of the fine grain structure. However, as the Al3Zr precipitates remains along grain boundaries, the superplastic capability of the material is not high. At 430°C with 1×10-4S-1 strain rate, the elongation obtained was 260%.
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