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High integrity cast aluminum components require the use of molten metal processing technologies prior to casting. These include processes such as degassing to reduce porosity, filtration to reduce inclusion content, addition of grain refiners to refine the grain structure, and the addition of chemical modifiers to alter the morphology of eutectic phases. Ultrasonic treatment (UST) is a novel processing method through which ultrasonic energy is introduced into molten metal for the purpose of degassing as well as modifying the cast microstructure. To optimize the use and applications of UST, it is necessary to examine the fundamental mechanisms and the limiting values of controlling parameters. The effectiveness of UST to perform a desired application within a molten metal is highly dependent on temperature, volume of liquid metal, and the state of the frequency in use. The mechanisms of ultrasonic energy imparted within molten metal will be discussed as well as the benefits of UST during molten metal processing. [ABSTRACT FROM AUTHOR]

Seafloor massive sulfides form in various marine hydrothermal settings, particularly within volcanic arcs, where magmatic fluids may contribute to the metal budget of the hydrothermal system. In this study, we focus on the Kolumbo volcano, a submarine volcanic edifice in the central Hellenic Volcanic Arc hosting an active hydrothermal system. Diffuse sulfate-sulfide chimneys form a Zn-Pb massive sulfide mineralization with elevated As, Ag, Au, Hg, Sb, and Tl contents. These elements have similar behavior during magmatic degassing and are common in arc-related hydrothermal systems. Trace-element data of igneous magnetite, combined with whole rock geochemistry and numerical modelling, highlights the behavior of chalcophile and siderophile elements during magmatic differentiation. We report that, despite early magmatic sulfide saturation, chalcophile element contents in the magma do not decrease until water saturation and degassing has occurred. The conservation of chalcophile elements in the magma during magmatic differentiation suggests that most of the magmatic sulfides do not fractionate. By contrast, upon degassing, As, Ag, Au, Cu, Hg, Sb, Sn, Pb, and Zn become depleted in the magma, likely partitioning into the volatile phase, either from the melt or during sulfide oxidation by volatiles. After degassing, the residual chalcophile elements in the melt are incorporated into magnetite. Trace-element data of magnetite enables identifying sulfide saturation during magmatic differentiation and discrimination between pre- and post-degassing magnetite. Our study highlights how magmatic degassing contributes to the metal budget in magmatic-hydrothermal systems that form seafloor massive sulfides and shows that igneous magnetite geochemistry is a powerful tool for tracking metal-mobilizing processes during magmatic differentiation. [ABSTRACT FROM AUTHOR]

From integrated textural and compositional studies of auriferous and barren pyrite/marcasite in the epithermal Axi gold deposit, China, we have identified a relationship between multiple gold mineralizing events, mafic magma recharge, and fluid-rock reactions. Three generations of pyrite (Py1–3) and four generations of marcasite (Mar1–4) record episodic gold mineralizing events, followed by silver-copper-lead-zinc-cadmium enrichment. The gold mineralizing events are recorded by high concentrations of subnanometer-sized gold in Py1, Py3, and Mar3 (max. = 147, 129, and 34 ppm, med. = 39, 34, and 12 ppm). Based on previous Re-Os age determinations of pyrite and U-Pb zircon ages of the andesitic wallrock, these gold events slightly postdate pulsed mafic magma recharge and represent the incursion of Au-As-S-rich magmatic volatiles into circulating meteoric water. Silver-Cu-Pb-Zn-Cd enrichment in Py2, Mar2, and Mar4 are consistent with quiescent degassing and gradual Ag-Cu-Pb-Zn-Cd enrichment in an evolved felsic magma. Barren Mar1 records the dominance of meteoric water and a limited magmatic fluid contribution. High-Co-Ni-V-Cr-Ti contents in porous cores of Py1 and Mar2 are attributed to wall rock alteration and dissolution-reprecipitation. The results provide convincing evidence that the metal budget (especially for Au, Ag, Cu, Pb, Zn, Sb) of the hydrothermal fluids and sulfides in epithermal systems are controlled by the influx of magmatic fluids and associated magma, whereas the enrichment of certain fluid-immobile elements, such as Co, Ni, V, Cr, and Ti, is caused in part by fluid-rock interaction. [ABSTRACT FROM AUTHOR]

The Miocene Climatic Optimum (MCO) from ~17 to 14 million years ago (Ma) represents an enigmatic reversal in Cenozoic cooling. A synthesis of marine paleotemperature records shows that the MCO was a local maximum in global sea surface temperature superimposed on a period from at least 19 Ma to 10 Ma, during which global temperatures were on the order of 10°C warmer than at present. Our high-resolution global reconstruction of ocean crustal production, a proxy for tectonic degassing of carbon, suggests that crustal production rates were ~35% higher than modern rates until ~14 Ma, when production began to decline steeply along with global temperatures. The magnitude and timing of the inferred changes in tectonic degassing can account for the majority of long-term ice sheet and global temperature evolution since 20 Ma. [ABSTRACT FROM AUTHOR]

The goal of metal injection molding (MIM) and metal additive manufacturing (metal AM) is the same--to make durable, high-quality metal components, implants, instruments, and other devices. Both methods offer medical [...]

Ban Chiang, Northeast Thailand, Volume 2A: Background to the study of the metal remains Edited by JOYCE C. WHITE and ELIZABETH G. HAMILTON Philadelphia: University of Pennsylvania Museum of Archaeology [...]

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High-shear melt conditioning (HSMC) technology was used for degassing and de-ironing of an aluminum alloy recovered from the Zorba cast fraction of the non-ferrous scrap from shredded end-of-life vehicles. The results showed that the recovery of aluminum alloys from the Zorba cast fraction was more than 80%. High-shear melt conditioning improved the degassing process during melt treatment in comparison with the adding of degassing tablets. The efficiency of the de-ironing process using HSMC increased by up to 24% after, increasing the Mn content to 0.8% in the melt. Adding Mn to Zorba melt enhanced the de-ironing process and eliminated the formation of β-AlFeSi intermetallic particles, which have a detrimental effect on both the mechanical and corrosion properties of the alloy. [ABSTRACT FROM AUTHOR]

We present a mathematical model of nonreactive fluid flow in a compacting porous medium. The model differs from previous formulations by considering fluid transport in the frame of reference moving with the solid phase. Such an approach guarantees material balance for the fluid and solid phases not only in the small‐porosity limit but also for large values of porosity. Using the numerical implementation of the proposed model, we simulate magmatic fluid transport in the Earth's upper crust. We account for the thermal softening of rocks, the plastic deformation of the solid matrix through decompaction weakening, and realistic fluid properties in a wide range of depths, including those above and below the brittle‐ductile transition (BDT). We show that our simulation approach can resolve the localized flow in the ductile zone and numerous hydrothermal convection cells in the brittle zone. We investigate the influence of decompaction weakening on high‐porosity channels forming in the ductile zone and their interaction with the convection in the brittle zone. We show that compaction causes magmatic fluid focusing and accumulation in high‐porosity lenses beneath the low‐porosity BDT zone. We show that magmatic fluid transfer through the BDT occurs mainly through the roofs of the lenses, which results in a plume of hydrothermal convection always sitting atop every lens. Other plumes between the lenses are associated with the convection of meteoric water that transfers only heat from the BDT to the surface. The simulations indicate that the lenses can be tracked by measuring certain parameters at the surface. Plain Language Summary: Magma cooling and degassing cause large volumes of hot water to exsolve. We investigate the flow of this magmatic fluid to the Earth's surface through permeable rocks. We account for complicated deformations of rocks and associated pore space closing and opening, that is, compaction and decompaction, which causes a spontaneous channelization of the flow at large depths. These channels interact with the meteoric water convection in the Earth's uppermost crust. We simulate this interaction and show that the magmatic fluid focuses and accumulates in high‐porosity lenses at a shallow depth. Most of the fluid flows through these lenses and escapes to the surface through their roofs. Thus, the lenses can be associated with regions of ore deposit formation. Above the lenses, the magmatic fluid mixes with the meteoric water, causing a convective plume of ascending water to sit above each lens. Therefore, the magmatic fluid reaches the surface in narrow areas that can be associated with hot springs. Key Points: We simulate magmatic fluid transport above, below, and through the brittle‐ductile transition (BDT)Interaction with meteoric convection causes fluid focusing below the BDT in high‐porosity lensesMagmatic fluid transport through BDT occurs mainly through the roofs of the lenses [ABSTRACT FROM AUTHOR]