Wyniki wyszukiwania - BazTech

1

The formation of new (Al, Zn)3Zr precipitates in an Al-Zn-Mg-Cu aluminum alloy after aging treatment and their response to dynamic compression

Khan Muhammad Abubaker, Wang Yangwei, Afifi Mohamed A., Tabish Mohammad, Hamza Muhammad, Yasin Ghulam, Ahmad Tahir, Liao Wei‑Bing

Archives of Civil and Mechanical Engineering

|

2023

|

Vol. 23, no. 1

art. no. e33, 2023

EN

This study mainly focuses on the newly developed (Al, Zn)3Zr precipitates through double aging treatment in an Al-Zn-Mg-Cu alloy (Al alloy) and their response to dynamic compression. The results show that the strength of the Al alloy after aging treatment (393 K for 8 h + 433 K for 10 h) is increased with an increasing strain rate from 1.0 x 10−3 to 3.0 x 103s−1 assisted by the strain hardening rate effect. The microstructures of Al alloy after the double aging treatment and dynamic compression at ~ 3.0 x 103s−1 contain novel (Al, Zn)3Zr precipitate with LI2 ordered and tetragonal structures. The small inter-particle spacing of precipitates after double aging, solute diffusion during the aging treatment, and dynamic compression lead to the overlapping of the different precipitates. For instance, the overlapping of (Al, Zn)3Zr and θ′ precipitates is observed. The overlapped (Al, Zn)3Zr contains Cu solutes, while the θ′ precipitate contains Zr solutes assisted by solute diffusion through dislocations and the increase in temperature during the compression. Besides, the number and size of the platelet precipitates are also increased after the dynamic compression compared to the double aging treatment Al alloy. In this research, the newly observed (Al, Zn)3Zr precipitate after double aging treatment, and post-high strain rate compression is suitable for successfully tailoring the precipitation of Al-Zn-Mg-Cu alloy and achieving optimum properties in the near future.

2

Study of the Influence of Additions on the Formation of Microstructure of Al-Zn-Mg-Cu Alloys

Pisarek B. P., Czekaj E., Pacyniak T.

Archives of Foundry Engineering

|

2018

|

Vol. 18, iss. 4

39--44

EN

The article presents the investigations of 7xxx aluminium alloys performed by the method of thermal and derivational analysis. The studies made it possible to identify the effect of the changes in the Cu concentration, the total Zn and Mg weight concentrations and the Zn/Mg weight concentration ratio on their crystallization process: the cooling as well as the kinetics and dynamics of the thermal process of cooling and crystallization. Metallographic studies were performed on the microstructure of the examined alloys and their HB hardness was measured. The evaluation of the changes was presented in reference to the model alloys EN AW-7003 and EN AW-7010, whose microstructure under the conditions of thermodynamic equilibrium are described by the phase diagrams: Al-Zn-Mg and Al-Zn-Mg-Cu. The performed investigations confirmed that the hardness HB of the examined alloys is mainly determined by the reinforcement of the matrix αAl by the introduced alloy additions and the presence of phases Θ(Al2Cu) and S(Al2CuMg) rich in copper, as well as η(MgZn2), in the examined alloys' microstructure. The increase of the amount of intermetallic phases precipitated in the microstructure of the examined alloys is caused, beside Cu, by the characteristic change of Zn wt. concentration and Mg. It was proposed that the process of one-stage thermal treatment of the examined alloys be introduced at a temperature of up to tJ-20 °C, which will prevent the exceedance of the solidus temperature.

3

Microstructure And Mechanical Properties Of An Al-Zn-Mg-Cu Alloy Produced By Gravity Casting Process

Saikawa S., Aoshima G., Ikeno S., Morita K., Sunayama N., Komai K.

Archives of Metallurgy and Materials

|

2015

|

Vol. 60, iss. 2A

871--874

EN

High-strength aluminum alloy are widely used for structural components in aerospace, transportation and racing car applications. The objective of this study is to enhance the strength of the Al-Zn-Mg-Cu alloy used for gravity casting process. All alloys cast into stepped-form sand mold (Sand-mold Casting; SC) and Y-block shaped metal mold(Permanent mold Casting; PC) C and then two –step aged at 398-423 K after solution treated at 743 K for 36 ks. The tensile strength and total elongation of the two-step aged SC alloys were 353-387 MPa and about 0.4% respectively. This low tensile properties of the SC alloys might be caused by remaining of undissolved crystallized phase such as Al2CuM, MgZn2 and Al-Fe-Cu system compounds. However, good tensile properties were obtained from PC alloys, tensile strength and 0.2% proof stress and elongation were 503-537 MPa, 474-519 MPa and 1.3-3.3%. The reason of the good properties in PM alloys, is the lowed amount of undissolved crystallized phase than that of SC ones and primary crystallized alpha-Al phase was finer due to high cooling rate at solidification in casting.

PL

Stopy glinu o wysokiej wytrzymałości są szeroko stosowane jako elementy konstrukcyjne w lotnictwie, w transporcie oraz w samochodach wyścigowych. Celem badań prezentowanych w niniejszej pracy jest zwiększenie wytrzymałości stopu Al-Zn-Mg-Cu przy zastosowaniu metody odlewania grawitacyjnego. Stopy odlewano w formie piaskowej (ang. Sand-mold Casting; SC) oraz w formie metalowej w kształcie Y (ang. Permanent mold Casting; PC), a następnie poddawano dwustopniowemu starzeniu w zakresie temperatur 398-423 K po przesycaniu w 743 K w czasie 36 ks. Wytrzymałość na rozciąganie stopów SC po dwustopniowym starzeniu wyniosła 353-387 MPa, natomiast całkowite wydłużenie – ok. 0,4%. Niska wytrzymałość stopów SC na rozciąganie może być spowodowana pozostałościami faz krystalicznych, tj. związków Al2CuM, MgZn2 i Al-Fe-Cu. Natomiast stopy PC charakteryzowały się dobrymi właściwościami mechanicznymi. Wytrzymałość na rozciąganie, umowna granica plastyczności R0.2, plastyczność oraz wydłużenie wyniosły odpowiednio 503-537MPa, 474-519MPa oraz 1,3-3,3%. Lepsze właściwości mechaniczne stopów PC można wytłumaczyć mniejszą ilością nierozpuszczonych faz krystalicznych w porównaniu ze stopami SC oraz mniejszą grubością głównej fazy krystalicznej alfa-Al wynikającej z wysokiej szybkości chłodzenia do punktu krzepnięcia przy odlewaniu.

4

The Properties of 7xxx Series Alloys Formed by Alloying Additions

Kwak Z., Rzadkosz S., Garbacz-Klempka A., Perek-Nowak M., Krok W.

Archives of Foundry Engineering

|

2015

|

Vol. 15, iss. 2

59--64

EN

Currently there is a constant development in the field of aluminium alloys engineering. This results from, i.a., better understanding of the mechanisms that direct strengthening of these alloys and the role of microalloying. Now it is microalloying in aluminum alloys that is receiving a lot of attention. It affects substantially the macro- and microstructure and kinetics of phase transformation influencing the properties during production and its exploitation. 7xxx series aluminum alloys, based on the Al-Zn-Mg-Cu system, are high-strength alloys, moreover, the presence of Zr and Sr further increases their strength and improves resistance to cracking. This study aims to present the changes of the properties, depending on the alloy chemical composition and the macro- and microstructure. Therefore, the characteristics in the field of hardness, tensile strength, yield strength and elongation are shown on selected examples. Observations were made on ingot samples obtained by semi-continuous casting, in the homogenized state. Samples were prepared from aluminum alloys in accordance with PN-EN 573-3: 2013. The advantage of Al-Zn-Mg-Cu alloys are undoubtedly good strength, Light-weight and resistance to corrosion. As widening of the already published studies it is sought to demonstrate the repeatability of the physical parameters in the whole volume of the sample.