Abstract
Al-Cu-Mg based alloys are renowned for their high strength and are extensively utilized in several industries, particularly aerospace. However, Al-Cu-Mg based alloys have certain drawbacks when it comes to its suitability for usage at increased temperatures, fluidity, hot tearing and resistance to corrosion. To address and prevent these issues, this study primarily aims to investigate the impact of copper (Cu), silver (Ag), and silicon carbide (SiC) concentrations on the microstructure, texture, and hardness of Al-Cu-Mg based alloys. Subsequently, the impact of adding 4 wt.% Cu, 0.7 wt.% Ag, and 1 wt.% SiC, either alone or in combination, on the aforementioned parameters was investigated. The alloys (Al-4Cu- 0.3Mg, Al-4Cu-0.3Mg-0.7Ag, and Al-4Cu-0.3Mg-0.7Ag-1SiC) were analyzed under the given conditions: (i) After solution treatment (T4) at a temperature of 540 °C for 6 hours;
(ii) after hot rolling at a temperature of 340 °C,
(iii) After hot rolling and then ageing at a temperature of 180 °C for 32 hours; and
(IV) After hot rolling and annealing at a temperature of 350 °C for 4 hours. The microstructure was examined by an optical microscope for the Al-4Cu-0.3Mg, Al-4Cu-0.3Mg-0.7Ag, and Al-4Cu-0.3Mg-0.7Ag-1SiC alloys.
Mechanically stirring during electrical resistance melting within a Nabertherm crucible furnace is therefore used to add SiC nanoparticle and achieve the Al composites. The sample with less Cu was discovered to have a large grain size and a low level of hardness, which can be attributed to the absence of the Al2Cu phase (precipitation hardening phase), indicating the importance of this phase in improving mechanical properties.
The addition of 4 wt.% Cu resulted in an increase in hardness, mostly attributed to the development of a substantial quantity of precipitates (Al2Cu). Adding a small amount (0.3 wt.%) of Mg to an Al-Cu alloy containing 4wt.% Cu makes the alloy harder. It also delays the formation of a particular type of microstructure (so-called Guinier-Preston (GP) zones) at a temperature of 180 °C. The addition of a third alloying element (such as Ag) to Al-Cu-Mg alloys increases their hardness through solid solution strengthening. This occurs when dislocations, or flaws in the crystal structure, are prevented from moving during deformation by the additional element's (solute atoms) distortion of the primary element's (solvent atoms) crystal lattice. A material's plastic deformation rate is determined by its dislocations; higher hardness results from greater resistance to their movement. As the Ag is able to improve the mechanical properties but in this case the addition of 0.7 wt.% Ag to an Al-4Cu-0.3Mg alloy results in an increased grain size and a decreased hardness, which can be attributed to the fact that (i) Ag may not be regarded to be effective for strengthening if it is very soluble in the material and forms a homogenous solid solution with little lattice deformation, and (ii) Ag influences recrystallization at high temperatures, which causes bigger grains to develop after heat treatment or Ag atoms may segregate to grain boundaries during processing, weakening the grain and increasing its susceptibility to grain growth.
After undergoing T4 treatment (540 °C for 6 hours), the grain size was reduced. Nevertheless, the alloy with Ag nevertheless displayed a greater grain size in comparison to the alloy without Ag. The addition of 0.667 wt.% and 1 wt.% SiC to an Al-4Cu-0.3Mg-0.7Ag alloy results in the alloy having a more refined structure and increased hardness. In addition,the T6 treatment was also performed. The Al-4Cu-0.3Mg-0.7Ag-1SiC alloy exhibits the highest hardness values, and the Ω phase demonstrates an exceptional heat stability during a period up to 32 hours.
The alloys (Al-4Cu-0.3Mg, Al-4Cu-0.3Mg-0.7Ag, and Al-4Cu-0.3Mg-0.7Ag-1SiC) were subjected to hot rolling at a temperature of 340 °C, with thicknesses of 1 mm and 5 mm, respectively. After the rolling process, the microstructure becomes too small to be analyzed using optical microscopy. Therefore, scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) was used to investigate the microstructure and texture. The specimens' hardness reduces after rolling, irrespective of subsequent treatments, in comparison to the initial alloy.
The three rolled samples were annealed at a temperature of 350 °C for durations of 1, 2, 3, and 4 hours, respectively. After a duration of 4 hours, the experimental findings indicate that the alloy with SiC exhibits a higher level of hardness compared to the other alloys without SiC.
This study provides a thorough analysis of how the addition of alloying elements (Cu, Mg, Ag, SiC) and the process of hot rolling affect the microstructure and hardness of Al-Cu-Mg based alloy.
(ii) after hot rolling at a temperature of 340 °C,
(iii) After hot rolling and then ageing at a temperature of 180 °C for 32 hours; and
(IV) After hot rolling and annealing at a temperature of 350 °C for 4 hours. The microstructure was examined by an optical microscope for the Al-4Cu-0.3Mg, Al-4Cu-0.3Mg-0.7Ag, and Al-4Cu-0.3Mg-0.7Ag-1SiC alloys.
Mechanically stirring during electrical resistance melting within a Nabertherm crucible furnace is therefore used to add SiC nanoparticle and achieve the Al composites. The sample with less Cu was discovered to have a large grain size and a low level of hardness, which can be attributed to the absence of the Al2Cu phase (precipitation hardening phase), indicating the importance of this phase in improving mechanical properties.
The addition of 4 wt.% Cu resulted in an increase in hardness, mostly attributed to the development of a substantial quantity of precipitates (Al2Cu). Adding a small amount (0.3 wt.%) of Mg to an Al-Cu alloy containing 4wt.% Cu makes the alloy harder. It also delays the formation of a particular type of microstructure (so-called Guinier-Preston (GP) zones) at a temperature of 180 °C. The addition of a third alloying element (such as Ag) to Al-Cu-Mg alloys increases their hardness through solid solution strengthening. This occurs when dislocations, or flaws in the crystal structure, are prevented from moving during deformation by the additional element's (solute atoms) distortion of the primary element's (solvent atoms) crystal lattice. A material's plastic deformation rate is determined by its dislocations; higher hardness results from greater resistance to their movement. As the Ag is able to improve the mechanical properties but in this case the addition of 0.7 wt.% Ag to an Al-4Cu-0.3Mg alloy results in an increased grain size and a decreased hardness, which can be attributed to the fact that (i) Ag may not be regarded to be effective for strengthening if it is very soluble in the material and forms a homogenous solid solution with little lattice deformation, and (ii) Ag influences recrystallization at high temperatures, which causes bigger grains to develop after heat treatment or Ag atoms may segregate to grain boundaries during processing, weakening the grain and increasing its susceptibility to grain growth.
After undergoing T4 treatment (540 °C for 6 hours), the grain size was reduced. Nevertheless, the alloy with Ag nevertheless displayed a greater grain size in comparison to the alloy without Ag. The addition of 0.667 wt.% and 1 wt.% SiC to an Al-4Cu-0.3Mg-0.7Ag alloy results in the alloy having a more refined structure and increased hardness. In addition,the T6 treatment was also performed. The Al-4Cu-0.3Mg-0.7Ag-1SiC alloy exhibits the highest hardness values, and the Ω phase demonstrates an exceptional heat stability during a period up to 32 hours.
The alloys (Al-4Cu-0.3Mg, Al-4Cu-0.3Mg-0.7Ag, and Al-4Cu-0.3Mg-0.7Ag-1SiC) were subjected to hot rolling at a temperature of 340 °C, with thicknesses of 1 mm and 5 mm, respectively. After the rolling process, the microstructure becomes too small to be analyzed using optical microscopy. Therefore, scanning electron microscopy (SEM) with electron backscatter diffraction (EBSD) was used to investigate the microstructure and texture. The specimens' hardness reduces after rolling, irrespective of subsequent treatments, in comparison to the initial alloy.
The three rolled samples were annealed at a temperature of 350 °C for durations of 1, 2, 3, and 4 hours, respectively. After a duration of 4 hours, the experimental findings indicate that the alloy with SiC exhibits a higher level of hardness compared to the other alloys without SiC.
This study provides a thorough analysis of how the addition of alloying elements (Cu, Mg, Ag, SiC) and the process of hot rolling affect the microstructure and hardness of Al-Cu-Mg based alloy.
Translated title of the contribution | Entwicklung des Mikrogefüges einer Al-Cu-Mg-Basislegierung während des Walzen und Glühen |
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Original language | English |
Qualification | Dipl.-Ing. |
Awarding Institution |
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Supervisors/Advisors |
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Award date | 20 Dec 2024 |
DOIs | |
Publication status | Published - 2024 |
Bibliographical note
no embargoKeywords
- Al-Cu-Mg based alloys
- SiC
- heat treatment
- rolling