ZnAl22Cu3 Alloy Research Articles

Influence of heat treatment on the structure, hardness and strength of ZnAl40Cu3 alloy

AbstractThis paper presents the results of studies on the effects of thermal treatment on the structure, hardness and strength of a high-aluminium monotectoid ZnAl40Cu3 alloy. The alloy was tested in the following conditions: after supersaturation at a temperature of 385 °C; after supersaturation at a temperature of 385 °C and subsequent ageing at temperatures of 125, 150 and 175 °C; and after annealing at a temperature of 185 °C. The studies revealed that annealing at a temperature of 185 °C causes a decrease in hardness and strength of ZnAl40Cu3 alloy. In contrast, the highest increase in hardness and strength was obtained by “incomplete” supersaturation at a temperature of 385 °C for 10 h. The increase in hardness and strength of the ZnAl40Cu3 alloy observed in the result of “incomplete” supersaturation at a temperature of 385 °C for 10 h may be connected with, most of all, formation of a quasi-dendritic structure. It was found that ageing of supersaturated samples causes a decrease in their hardness when compared to that of the samples after supersaturation.

Influence of Solution Heat Treatment on Structure and Mechanical Properties of ZnAl22Cu3 Alloy

Abstract The influence of solution heat treatment at 385°C over 10 h with cooling in water on the structure, hardness and strength of the ZnAl22Cu3 eutectoid alloy is presented in the paper. The eutectoid ZnAl22Cu3 alloy is characterized by a dendritic structure. Dendrites are composed of a supersaturated solid solution of Al in Zn. In the interdendritic spaces a eutectoid mixture is present, with an absence of the ε (CuZn4) phase. Solution heat treatment of the ZnAl22Cu3 alloy causes the occurrence of precipitates rich in Zn and Cu, possibly ε phase. Solution heat treatment at 385°C initially causes a significant decrease of the alloy hardness, although longer solution heat treatment causes a significant increase of the hardness as compared to the as-cast alloy.

An Influence of Ageing on the Structure, Corrosion Resistance and Hardness of High Aluminum ZnAl40Cu3 Alloy

Zn-Al-Cu alloys are used primarily because of their tribological properties as an alternative material for bronze, cast iron and aluminum alloy bearings and as a construction material. Particularly interesting are high aluminum zinc alloys. Monoeutectic zinc and aluminum alloys are characterized by the highest hardness, tensile strength and wear resistance of all of the zinc alloys. A significant problem with the use of the Zn-Al-Cu alloys is their insufficient resistance to electrochemical corrosion. Properties of Zn-Al-Cu alloys can be improved by heat treatment. The purpose of examination was to determine the effect of heat treatment (aging at various temperatures) on the microstructure and corrosion resistance of the ZnAl40Cu3 alloy. The scope of the examination included: structural examinations, determination of hardness using Brinell’s method and corrosion resistance examinations. Ageing at higher temperatures causes a creation of areas where is an eutectoid mixture. The study showed that ageing causes a decrease in hardness of ZnAl40Cu3 alloy. This decrease is even greater, when the temperature of ageing is lower. The studies have shown a significant influence of ageing on the corrosion resistance of the alloy ZnAl40Cu3. Maximum corrosion resistance were characterized by the sample after ageing at higher temperatures.

An Influence of the Self-Ageing on the Hardness and Corrosion Resistance of the ZnAl22Cu3 and ZnAl40Cu3 Alloys

The purpose of the examination was to determination of influence of self - ageing on the hardness and corrosion resistance of Zn - Al - Cu alloys. Subject of test were ZnAl22Cu3 and ZnAl40Cu3 alloys. The scope of examinations included: Brinell hardness tests and corrosion resistance tests. Tests were carried out just after heat treatment and after duration of 1, 2, 3, 4 and 5 months after heat treatment. The scope of corrosion test included galvanostatic and potentiodynamic tests. It was found, that natural ageing causes significant decrease of the hardness of ZnAl22Cu3 and ZnAl40Cu3 alloys after solution heat treatment. Carried out tests pointed out, that natural ageing significantly influences on corrosion resistance of ZnAl22Cu3 and ZnAl40Cu3 alloys. During ageing process, corrosion resistance is significantly changed. The high aluminum ZnAl 40Cu3 alloy as a higher hardness and higher corrosion resistance than ZnAl22Cu3 alloy

Influence of Solutionizing Parameters on the Structure and Corrosion Resistance of the ZnAl40Cu3 Alloy

The purpose of carried out examination was to determine the effect of solution heat treatment on the structure and corrosion resistance of the ZnAl40Cu3 alloy in the "acid rain" environment. The scope of the test included Brinell hardness tests, structural tests and galvanostatic and potentiodynamic tests. The examination showed that the maximum hardness of the sample after solution heat treatment obtain after 10 h of solutionizing. It has been shown that the solutionizing increases the corrosion resistance. The corrosion resistance was greater, when the longer was the time of solutionizing.

Erosion Resistance of the ZnAl22Cu3 Alloy

The aim of this study was to determine the effect of soaking on the erosion resistance of ZnAl22Cu3 alloy. The following samples were examined: as-cast, soaked at 185 °C and after solutionizing at a temperature of 385 °C. The scope of the examination included: Brinell hardness test, test of resistance to erosion and the examination of the surface of the samples after erosion tests. The examination showed a high resistance to erosion of ZnAl22Cu3 alloy. Heat treatment had no significant effect on the erosion resistance of the tested alloy. A significant impact on erosion resistance exerted the abrasive incidence angle. Consumption was greater when the angle of incidence was lower.

The Influence of the Solutionizing and Ageing on the Structure and Hardness of the ZnAl40Cu3 Alloy

Zn-Al alloys are mainly used due to their tribological properties as an alternative material for bronze, cast irons and aluminum in a bearings and as a construction material. Particular interesting is Zn-40Al-3Cu alloy due to its features. Improvement of the alloy’s features can be obtained by silicon addition, plastic working, heat treatment – solutionizing and ageing. In the article have been shown results of the ZnAl22Cu3 alloy examination as - cast and subjected solutionizing and ageing 385 oC/10h + 175 oC/1h and 385 oC/10h + 175 oC/10h. The scope of examination included: structure testing using scanning microscope, X - ray microanalysis, hardness test. There was found significant decrease of hardness of the tested alloy. Structural examinations have shown that initially in the structure were visible precipitates reach in aluminum and copper. Also were visible precipitates reach in zinc. With increasing time of soaking at 175 oC precipitates reach in aluminum and copper disappeared.

Structure and mechanical properties of ZnAl40Cu3 alloy modified with rare earth elements

The influence of modification of rare earth elements on the structure and mechanical properties of ZnAl40Cu3 alloy is presented in this paper. The ZnAl40Cu3, ZnAl40Cu3SiM and ZnAl40Cu3Si (modified alloy) alloys were tested. The ZnAl40Cu3Si and ZnAl40Cu3 alloys were characterized and revealed a heterogeneous, fine‐grained, dendritic structure. The structure of the alloy ZnAl40Cu3SiM was much more homogeneous. It was found that the addition of silicon reduces the tensile strength. Addition of rare earth elements (REE) to the alloy with silicon resulted in the re‐growth of strength. It was also found that the modification of rare earth elements increases the hardness of the alloy.

Influence of Heat Treatment on the Hardness of ZnAl22Cu3 Alloy

The effect of heat treatment on the structure and hardness of the ZnAl22Cu3 alloy is presented in the paper. ZnAl22 and ZnAl22Cu3 alloys were tested. The scope of the examination included dilatometry, structural and hardness tests. Very interesting is the effect of the transformation, occurring at lower temperatures on the structure and hardness of the alloy. There are found, that soaking at 185°C causes a decrease in the hardness of the ZnAl22Cu3 alloy. Observed ZnAl22Cu3 alloy hardness decrease is related to the disappearance of zinc-rich dendrites and the transition of zinc to a eutectoid mixture.

Influence of Corrosion in "Acid Rain" on the Structure of Surface Layer of the ZnAl22Cu3 Alloy

The effect of corrosion in an "acid rain" (pH = 3.5) environment on the structure of the surface layer of the ZnAl22Cu3 alloy are presented in this study. Base alloy, alloy with silicon and alloy with silicon and rare earth elements were tested. The scope of the examination included potentiostatic tests in acid rain and studies of structure of surface layer of samples after corrosion tests. The studies have shown, that corrosion processes initially run quickly which leads to reduction of zinc in the surface layer and enriching in aluminum and copper so that the corrosion rate decreases. The presence of the silicon precipitates does not decrease the corrosion resistance of the ZnAl22Cu3 alloy in acid rain environment. The addition of rare earth elements improves the corrosion resistance of the ZnAl22Cu3 alloy in acid rain environment.

Influence of Copper Addition on Structure and Hardness of the ZnAl40Cu3 Alloy after Heat Treatment

The effect of heat treatment on the structure and hardness of the ZnAl240Cu3 alloy is presented in the paper. ZnAl40 and ZnAl40Cu3 alloys were tested. The scope of the examination included: dilatometry, structural and hardness tests. There are two transformations taking place during the heating and the reverse transformation during cooling. Most important for the alloy is the first transormation which occurs at lower temperatures (from 104°C to 131°C). There are found, that long-term soaking at 185°C results in a significant decrease in the hardness of the ZnAl40Cu3.alloy. The reason for the observed decrease in the hardness of the ZnAl40Cu3 alloy by soaking at a temperature of 185°C is primarily disappearance of dendrites.

Influence of Si and REE on the Corrosion Resistance of ZnAl40Cu3 Alloy

The corrosion resistance of ZnAl40Cu3 alloy are presented in the paper. Base alloy, alloy with silicon and alloy with silicon and rare earth elements were tested. The scope of the examination included: potentiodynamic and potentiostatic examinations, studies of the alloy surface condition after corrosion tests. The studies have shown, that the addition of rare earth elements improves the corrosion resistance of the ZnAl40Cu3 alloy in 3% NaCl environment. The presence of the silicon precipitates does not decrease the corrosion resistance of the ZnAl40Cu3 alloy in the 3% NaCl environment

Influence of Corrosive Environment on Changes of the ZnAl40Cu3 Upper Alloy Layer

Zn-Al alloys are used mainly because of their tribological properties as a material alternative to bronze, cast iron and aluminum alloys in bearings, and as a structural material. Improved properties of Zn-Al alloys can be obtained by the addition of copper , silicon and using of heat treatment. Tribological properties of alloys of the Zn-Al-Cu alloys, their structure has been well described in the literature. Far less are, however, studies on the effect of corrosive environments on the structure of the surface layer of the alloy. The purpose of this examination was to determine the effect of corrosive environment on the surface layer of the ZnAl22Cu3 alloy. Subject of examination was the unmodified alloy containing 40% Al mass. and 3%. Cu (Zn - remain). The tested alloy was subject of the following operations: soaking at the temperature of 185°C during 10 hours with cooling in water, soaking at the temperature of 380°C during 10 hours with cooling in water and soaking at the temperature of 380°C w during10 hours with subsequent soaking at the temperature of 170°C with cooling in water. Subject of tests structural examination were samples after potentiostatic tests carried out at potential E = 300 mV Ekor in 24 hours in an acid rain, pH = 3.5. In order to determine the microstructure of the examined coatings metallographic examinations were performed using optical and scanning microscope cooperating with EDS X-ray spectrometer. Quantitative analysis of the selected characteristic microareas determined from X-ray spectral analysis EDX.

Influence of Heat Treatment on Corrosion Resistance of the ZnAl<sub>22</sub>Cu<sub>3</sub> Alloy

Zn-Al-Cu type alloys are characterized by a number of advantageous properties which include: good castability, good tribological properties, low energy value needed for forming of the product. As compared to bronze, Al-Zn-Cu alloys are characterized by a lower density. Improved properties of Zn-Al alloys can be obtained by addition of copper and silicon. Advantageous results can also be obtained by heat treatment. There is an extensive literature on the effect of heat treatment upon the structure of Al-Zn-Cu alloys. However, few articles discuss the effect of heat treatment on the corrosion resistance of alloys. The purpose of this examination was to determine the effect of heat treatment on corrosion resistance of ZnAl22Cu3 alloy. The unmodified alloy containing 22% Al mass. and 3%. Cu (Zn - remain) was subjected to the examinations. Tested alloys underwent the following operations: soaking at the temperature of 185°C for 10 hours with cooling in water, soaking at the temperature of 380°C for 10 hours with cooling in water and soaking at the temperature of 380°C for 10 hours with subsequent soaking at the temperature of 170°C with cooling in water. Potentiodynamic and potentiostatic examinations in a solution of acid rain with pH = 3.5 were carried out. Then the tests were followed by examination of the corroded sample surface.The carried out examinations showed a decrease in corrosion resistance after heat treatment at the temperature of 380°C and a slight increase after heat treatment at the temperature of 185°C.

Effect of Cooling Rate on the Porosity of the ZnAl22Cu3 Alloy

Zn-Al-Cu alloys are characterized by advantageous set of functional quality futures: tribological, strength, corrosion. They are used as an alternative material for bronze, cast iron and aluminum alloys in bearings and as a structural material. Properties of Zn-Al-Cu can be improved by partial or total replacement of copper with silicon and addition of rare - earth elements. Previous studies of the current authors have shown a significant effect of cooling rate on the structure of the ZnAl22Cu3 alloy. The presence of pores and significant differences in porosity between samples slowly and fast cooled has been found. The aim of this study was to determine the effect of cooling conditions on the pore formation in ZnAl22Cu3 alloy. The article presents the structure of the slowly and fast cooled alloy. Structural examinations were carried out on samples taken from the top, center and bottom of the ingot. In order to determine the microstructure metallographic tests were carried out using optical microscope and electron scanning microscope. Through EDS X-ray spectrometry quantitative analysis of characteristic microareas was performed as well. In order to assess the morphological characteristics of the pore a computer program Met-Ilo developed in the Department of Materials Science, Silesian University of Technology has been used. Changes of the volume fraction and the average area on a flat cross section in particular areas of the ingot were analyzed quantitatively.