Brass Alloys

We study a nanocrystalline AlCrCuFeNiZn high-entropy alloy synthesized by ball milling followed by hot compaction at 600 °C for 15 min at 650 MPa. X-ray diffraction reveals that the mechanically alloyed powder consists of a solid solution bcc matrix containing 12 vol.% fcc phase. After hot compaction, it consists of 60 vol.% bcc and 40 vol.% fcc. Composition analysis by atom probe tomography shows that the material is not a homogeneous fcc-bcc solid solution but instead a composite of bcc structured Ni-Al, Cr-Fe, and Fe-Cr based regions and of fcc Cu-Zn based regions. The Cu-Zn rich phase has 30 at.% Zn α-brass composition. It segregates predominantly along grain boundaries thereby stabilizing the nanocrystalline microstructure and preventing grain growth. The Cr and Fe rich bcc regions were presumably formed by spinodal decomposition of a Cr-Fe phase that was inherited from the hot compacted state. The Ni-Al phase remains stable even after hot compaction and forms the dominant bcc matrix phase. The crystallite sizes are in the range of 20-30 nm as determined by TEM. The hot compacted alloy exhibited very high hardness of 870 ± 10 HV. The results reveal that phase decomposition rather than homogeneous mixing is prevalent in this alloy. Hence, our current observations fail to justify the present high-entropy alloy design concept. Therefore, a more structure-and thermodynamics-guided strategy for designing high-entropy alloys is encouraged as a pathway towards exploiting the solid solution and stability idea inherent in this concept.

The aim of this study was to investigate the effects of immersion time on the electrochemical corrosion behaviour of three brass alloys in simulated acid rain at 25 o C, utilizing the electrochemical impedance spectroscopy (EIS). The main parameters of the corrosion process were established. The immersion of the alloys in simulated acid rain reduces the intensity of the corrosion process. For all the samples the polarization resistance (R p) is increasing with the immersion, from 1 minute to 1 hour and 1 day respectively. The EIS results exhibited relative capacitive behaviour (suitable corrosion resistance) with phase angle close to –70 o and relative large impedance values (order of 10 4 Ω cm 2) at low and medium frequencies, which are indicative of the formation of a stable oxide film on these brass samples in simulated acid rain. Equivalent circuits (EC) were used to modeling EIS data, in order to characterize samples surface.

The increasing demand for free-lead Cu30Zn alloy for all industrial applications has prompted to develop the grain size and formability. One of the major challenges facing the researcher and industry is decreasing the formability and machinability which requires continuous improvements in design and fabrication techniques. The current trend for free-lead Cu30Zn alloy in these categories is reviewed. Results show that developments in free-lead Cu30Zn alloy are affected by a lot of factors such as chemical composition, microstructure, grain size, strain and hardness. A highly developed system with characteristics of compromised decision making became more favorable and initiated an interesting intervention since the casting, cold working, and heat treatment is controlled.

Porous and nanoporous aluminum have been fabricated via selective dissolution. Al-Zn alloys were dealloyed in an aqueous solution of nitric acid to selectively dissolve zinc. Fast solidification methods permitted to adjust the precursor microstructure of the parent alloy in order to induce supersaturation of zinc in aluminum. An electric potential applied during corrosion affected the final morphology of porosity. Electronic imaging evinced the presence of regions with less than 100 nm diameter pores. This nanoporosity was only present in electrochemically dealloyed samples. We observed two types of porosity in dealloyed samples: a primary porosity resulting from the selective removal of zinc-rich interdendritic phases and a secondary porosity resulting from nanoporosity evolution inside zinc-supersaturated dendrites.

The recent environmental/health and safety regulations placed restrictions of use of hazardous substances on critical manufacturing sectors and consumers’ products. Brass alloys specifically face a challenging issue concerning the elimination of lead (Pb) which has been a critical element affecting both the machinability and overall quality and efficiency of their manufacturing process. The adaptation of novel materials and processing routes in the green economy constitutes a crucial decision for competitive business and industry growth as a worldwide perspective with substantial industrial and social impact. This paper aims to review the emergent innovative and sustainable material solutions in the manufacturing industry, in line with environmental regulations, by highlighting smart alloy design practices and promoting new and innovative approaches for material selection and manufacturing process optimisation. In this review we analyse the processing, structure and machinability as...

The use of lighter, more robust and highly recyclable materials are now widespread strategy when compared to existing materials. In the present study, casting of Aluminum Alloy with High Magnesium Content has been performed with addition of Boron, Strontium and Titanium elements. Castability and Bi-film index evolution have been studied.Traditional gravity casting have been selected as the casting method. Effect of temperature and constituents into spiral mold casting has been studied to assess flow behavior Solidification under vacuum conditions have been performed to evaluate bifilm index and metal oxide layers which are entrapped within the structure during casting and soldification. Tensile tests have been performed to evaluate mechanical strenght of the manufactured alloys.

Brasses belong to a group of copper-based alloys with a wide variety of important applications. Traditionally, lead was a necessary alloying element in brasses due to its ability to improve machining in terms of time and quality. Additional effect of lead is a wear reduce of machining tools. The main risk of using lead-containing brasses is lead’s toxicity for humans. Various stages of producing and machining of brasses may be harmful, so certain safety regulations are normally required, which is time and money expensive[1]. That’s why alternative technologies of producing lead-free brasses, using graphite, are of great interest. Carbon Nano-tubes (CNTs) can be considered as ideal reinforcements, due to their high specific strength, thermal, electrical and mechanical characteristics. In the present study brass (Cu-Zn)/carbon nanotubes (CNT) composites were produced by injection of CNTs in brass using high pressure die casting method. Current investigation demonstrates that more than...

In this study, grain refinement performance of as-cast Al using machining chip of Al instead of the grain refiner is investigated. At first, the machining chips of pure Al are placed in metallic mold. Then, pure Al melt is inserted into the mold with the machining chips. From the microstructure of the as-cast Al using the machining chips, it is found that this machining chip in mold can induce grain refinement of as-cast Al. The increment of the Al chips enhances the grain refinement of the as-cast Al. Moreover, it is shown that preheating the mold can reduce the pore inside as-cast Al using the machining chips. This grain-refinement effect by the machining chips would come from the enhancement of cooling rate and the role of the nucleation site. Therefore, it is concluded that the machining chips of Al can enhance the grain refinement of as-cast Al.

Brasses belong to a group of copper-based alloys with a wide variety of important applications. Traditionally, lead was a necessary alloying element in brasses due to its ability to improve machining in terms of time and quality. Additional effect of lead is a wear reduce of machining tools. The main risk of using lead-containing brasses is lead's toxicity for humans. Various stages of producing and machining of brasses may be harmful, so certain safety regulations are normally required, which is time and money expensive [1]. That's why alternative technologies of producing lead-free brasses, using graphite, are of great interest. Carbon Nanotubes (CNTs) can be considered as ideal reinforcements, due to their high specific strength, thermal, electrical and mechanical characteristics. In the present study brass (Cu-Zn)/carbon nanotubes (CNT) composites were produced by injection of CNTs in brass using high pressure die casting method. Current investigation demonstrates that more than 50% efficiency of direct injection of CNT in the brass has been achieved. The inserted CNTs have been partially dispersed in the metal matrix. Furthermore the friction coefficient significantly decreases with an increase of the amount of CNT content in the examined Cu-Zn brass alloy. Thus, the machinability improvement as a result of CNT performance in the examined Cu-Zn brass alloy is expected.

Actual request for environmental-friendly materials in electric and electronic equipment, has been released recently to some common metal materials with wide application in different areas, such as brasses, steels, etc. Therefore, some advanced trends are actual nowadays in the investigations of lead-free alternative for traditional free machining brasses and the review of current efforts in that field is presented in this paper.

The aim of this work is to evaluate the machinability of Pb-free brasses with Si from 1% to 4 wt%, which were prepared using Cu 60/Zn 40 and Cu 80/Si 20 Pb-free master alloys. Machinability of the investigated alloys is tested based on cutting force, tool wear, surface roughness, and chip type. In the 1 wt% Si alloy, which exhibits maximum strength, the maximum cutting force is measured and undesirable continuous chip type is produced, while tool wear and machined surface roughness have the lowest values. Increasing the silicon content from 1% to 4%, results in increasing the tool wear by 140%, machined surface roughness by 25%, while the chip type changed from continuous to discontinuous type, and the cutting force was reduced by 50%. Machinability results are correlated with the alloy mechanical properties and with the phases present in the microstructure.

It has been shown repeatedly that many elements present as traces or at low level can affect graphite shape in cast irons. As part of a long term project aimed at clarifying the growth and the alteration of spheroidal graphite, a study on the effect of a few elements (Cu, Sn, Sb, and Ti) on primary graphite growth was undertaken and analysed with reference to an alloy without any such additions. This work was performed by remelting alloys in graphite crucibles thus saturating the melt in carbon and enabling primary graphite to grow by controlled cooling of the melt above the eutectic temperature. Primary graphite growth in the reference alloy was observed to be lamellar, while the added elements were found to affect bulk graphite and to modify its outer shape, with Sb leading eventually to rounded agglomerates together with wavy lamellae. Secondary ion mass spectrometry was used to analyze the distribution of elements, and no build-up of trace elements at the graphite surface could ...

The aim of this work is to evaluate the machinability of Pb-free brasses with Si from 1% to 4 wt%, which were prepared using Cu 60/Zn 40 and Cu 80/Si 20 Pb-free master alloys. Machinability of the investigated alloys is tested based on cutting force, tool wear, surface roughness, and chip type. In the 1 wt% Si alloy, which exhibits maximum strength, the maximum cutting force is measured and undesirable continuous chip type is produced, while tool wear and machined surface roughness have the lowest values. Increasing the silicon content from 1% to 4%, results in increasing the tool wear by 140%, machined surface roughness by 25%, while the chip type changed from continuous to discontinuous type, and the cutting force was reduced by 50%. Machinability results are correlated with the alloy mechanical properties and with the phases present in the microstructure.

Three quaternary Al-6Si-3Cu-xMg (x = 0.59, 3.80, and 6.78 wt.%) alloys were produced by melt-spun and characterized using X-ray diffractometry (XRD), transmission electron microscopy (TEM), and microhardness techniques. Obtained second phases were Al 2 Cu(θ) for the alloy with 0.59% Mg and Al 5 Cu 2 Mg 8 Si 6 (Q) for the alloys with 3.80 and 6.78% Mg. These phases are present as 30-50 nm or as 5-10 nm nanoparticles. Alloying elements content in solid solution increased, mainly for Si and Mg. The high alloying elements content in solid solution and the small α-Al cell size for melt-spun alloys leads to microhardness values about 2 times higher than those of ingot counterparts. The microhardness increase for melt-spun alloys with 3.80 and 6.78% Mg depends on Mg content in solid solution.

The main objective of this paper was to assess three leaded brass samples (pending application with Copper Development Association) using optical microscopy and mass spectrometry to compare the distribution of lead. Based on the mass spectrometry data, a great deal of variation was not found within each of the samples based on five different sample locations. Optical microscopy, scanning electron microscopy and energy-dispersive X-ray spectroscopy confirmed that the lead was homogenously distributed in brass.

The Rietveld X-ray diffraction analysis was applied to analyze the weight fraction of precipitation phases and microstructure characterizations of rapidly solidified Al-8Zn-4Mg-Cu, = 1, 4, 8, and 10 alloys (in wt.%), prepared by melt spun technique. A good agreement between observed and calculated diffraction pattern was obtained and the conventional Rietveld factors ( , wp , and GOF) converged to satisfactory values. Solid solubilities of Zn, Mg, and Cu in -Al were extended to high values. Besides, metastable Al 0.71 Zn 0.29 , intermetallic Al 2 CuMg, Al 2 Cu, and CuMgZn phases have been observed for = 4, 8, and 10 Cu alloys. The crystal structure and microstructure characterizations exhibit strong Cu content dependence.

We have studied a nanocrystalline AlCrCuFeNiZn high-entropy alloy synthesized by ball milling followed by hot compaction at 600°C for 15 min at 650 MPa. X-ray diffraction reveals that the mechanically alloyed powder consists of a solid-solution body-centered cubic (bcc) matrix containing 12 vol.% face-centered cubic (fcc) phase. After hot compaction, it consists of 60 vol.% bcc and 40 vol.% fcc. Composition analysis by atom probe tomography shows that the material is not a homogeneous fcc-bcc solid solution but instead a composite of bcc structured Ni-Al-, Cr-Fe-and Fe-Cr-based regions and of fcc Cu-Zn-based regions. The Cu-Zn-rich phase has 30 at.% Zn a-brass composition. It segregates predominantly along grain boundaries thereby stabilizing the nanocrystalline microstructure and preventing grain growth. The Cr-and Fe-rich bcc regions were presumably formed by spinodal decomposition of a Cr-Fe phase that was inherited from the hot compacted state. The Ni-Al phase remains stable even after hot compaction and forms the dominant bcc matrix phase. The crystallite sizes are in the range of 20-30 nm as determined by transmission electron microscopy. The hot compacted alloy exhibited very high hardness of 870 ± 10 HV. The results reveal that phase decomposition rather than homogeneous mixing is prevalent in this alloy. Hence, our current observations fail to justify the present high-entropy alloy design concept. Therefore, a strategy guided more by structure and thermodynamics for designing high-entropy alloys is encouraged as a pathway towards exploiting the solid-solution and stability idea inherent in this concept.

Brasses belong to a group of copper-based alloys with a wide variety of important applications. Traditionally, lead was a necessary alloying element in brasses due to its ability to improve machining in terms of time and quality. Additional effect of lead is a wear reduce of machining tools. The main risk of using lead-containing brasses is lead’s toxicity for humans. Various stages of producing and machining of brasses may be harmful, so certain safety regulations are normally required, which is time and
money expensive[1].
That’s why alternative technologies of producing lead-free brasses, using graphite, are of great interest. Carbon Nano-tubes (CNTs) can be considered as ideal reinforcements, due to their high specific strength, thermal, electrical and mechanical characteristics.
In the present study brass (Cu-Zn)/carbon nanotubes (CNT) composites were produced by injection of CNTs in brass using high pressure die casting method. Current
investigation demonstrates that more than 50% efficiency of direct injection of CNT in the brass has been achieved. The inserted CNTs have been partially dispersed in the metal matrix. Furthermore the friction coefficient significantly decreases with an increase of the amount of CNT content in the examined Cu-Zn brass alloy. Thus, the machinability improvement as a result of CNT performance in the examined Cu-Zn brass alloy is expected.

The aim of this work is to evaluate the machinability of Pb-free brasses with Si from 1% to 4 wt%, which were prepared using Cu 60/Zn 40 and Cu 80/Si 20 Pb-free master alloys. Machinability of the investigated alloys is tested based on cutting force, tool wear, surface roughness, and chip type. In the 1 wt% Si alloy, which exhibits maximum strength, the maximum cutting force is measured and undesirable continuous chip type is produced, while tool wear and machined surface roughness have the lowest values. Increasing the silicon content from 1% to 4%, results in increasing the tool wear by 140%, machined surface roughness by 25%, while the chip type changed from continuous to discontinuous type, and the cutting force was reduced by 50%. Machinability results are correlated with the alloy mechanical properties and with the phases present in the microstructure.

Characterization of eleven copper alloy artifacts, dated between the 4th and 6th (or early 7th) centuries AD, retrieved from archeological excavations of remains associated with Samaritan sites along the central Coastal Plain of Israel, was performed. The assemblage includes three inscribed polygonal finger rings, four finger rings with decorated bezel (of which one bears a legend in the Samaritan script), two inscribed amulet pendants, and two thin cylindrical foils (containers of phylacteries, designated for the safekeeping of a magical or religious text written on papyri or parchment). The aim of this research is to use archeometallurgical non-destructive and destructive methods in order to determine manufacturing processes of the objects, and if possible their production place, their origin of ore and their use.

Brass has an attractive combination of properties, namely, good corrosion resistance, good wear properties, and high thermal and electrical conductivity. In this study, influence of selected alloy additions (Al and Ti) on performance of leaded brass alloys (CuZn39pb3) was investigated. The observation of microstructures, compression tests, and hardness tests were performed. The results of metallographic and mechanical tests indicate some influence of small amount additives of Al and Ti. Optical emission spectrometer (OES), light optical microscope (LOM), micro-Vickers hardness tester, and compression testing machine were used in this investigation. Consequently, Al had a significant effect on microstructure and mechanical properties of CuZn39Pb3 alloy. A larger compression strength at 0.31% wt of Al was obtained, as compared with the other alloys. Adding of Al and Ti led to the modification of the microstructure; thus, the compression strength was increased.

We studied a nanocrystalline AlCrCuFeNiZn high-entropy alloy synthesized by ball milling followed by hot compaction at
600 C for 15 min at 650 MPa. X-ray diffraction reveals that the mechanically alloyed powder consists of a solid-solution body-centered cubic (bcc) matrix containing 12 vol.% face-centered cubic (fcc) phase. After hot compaction, it consists of 60 vol.% bcc and 40 vol.% fcc. Composition analysis by atom probe tomography shows that the material is not a homogeneous fcc–bcc solid solution but instead a composite of bcc structured Ni–Al-, Cr–Fe- and Fe–Cr-based regions and of fcc Cu–Zn-based regions. The Cu–Zn-rich phase has 30 at.% Zn a-brass composition. It segregates predominantly along grain boundaries thereby stabilizing the nanocrystalline microstructure and preventing grain growth. The Cr- and Fe-rich bcc regions were presumably formed by spinodal decomposition of a Cr–Fe phase that was inherited from the hot compacted state. The Ni–Al phase remains stable even after hot compaction and forms the dominant bcc matrix phase. The crystallite sizes are in the range of 20–30 nm as determined by transmission electron microscopy. The hot compacted alloy exhibited very high hardness of 870 ± 10 HV. The results reveal that phase decomposition rather than homogeneous mixing is prevalent in this alloy. Hence, our current observations fail to justify the present high-entropy alloy design concept. Therefore, a strategy guided more by structure and thermodynamics for designing high-entropy alloys is encouraged as a pathway towards exploiting the solid-solution and stability idea inherent in this concept."