Shear Assisted Processing and Extrusion (ShAPE) enables the extrusion of many alloys with enhanced properties. In this study, ShAPE was used to extrude tubes of aluminum alloy 6063 measuring 12 mm in ...diameter at extrusion speeds up to 3.8 m/min, an increase of 10 times over what has previously been reported for ShAPE. Increasing the extrusion speed from 0.7 to 3.8 m/min resulted in using 68% less process energy at steady state without any loss in mechanical properties.
As-extruded tubes had ultimate tensile strengths on par with conventional T5 extrusions and double the elongation at break. ShAPE extruded tubes that underwent a T5 heat treatment had yield and ultimate strengths of 198 and 234 MPa, respectively, which is ~30% higher than standard T5 material and comparable to T6 properties.
Microstructural analyses were performed on as-extruded and T5 treated tubes. Grain refinement below 20 μm was identified, with no detectable growth of macroscale Mg2Si strengthening precipitates. Nanoscale β″ was not observed in the as-extruded materials but was prominent after T5 heat treatment suggesting that β″ strengthening precipitates were solutionized in situ during the ShAPE process. The ability to perform solution heat treating in situ, rather than post-extrusion, eliminates an energy intensive process step and is applicable to a wide variety of alloys.
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•Shear Assisted Processing and Extrusion (ShAPE) was used to produce AA 6063 tubing.•Maximum extrusion speeds of 3.8 m/s were achieved, over 10 times faster than any previous friction extrusion.•Energy efficiency increased with extrusion speed, reaching up to 42% at steady state.•ShAPE Extrusions with a T5 heat treatment achieved mechanical properties on par with a traditional T6 heat treatment.•ShAPE + T5 resulted in peak to slightly over-aged microstructure, similar to a conventional T6 microstructure.
•Mg alloy (AZ31) shows better corrosion resistance after laser surface processing.•Laser surface processing changes mode of corrosion from localized to uniform.•Laser surface processing creates ∼0.5 ...μm thick mixed-metal oxide surface film.•Mixed-metal oxide surface film converts to layered double hydroxide film later.
Despite their excellent strength-to-weight ratio, wider use of magnesium (Mg) alloys for light-weight applications is limited by their poor corrosion resistance, especially in chloride-containing environments. The present study shows improved corrosion resistance imparted by laser surface processing (LSP) of a commercial AZ31 (Mg-3Al-1Zn) alloy. Nanosecond laser processing at three different power settings was carried out on the surface of a 1-mm-thick rolled AZ31 sheet. Electrochemical studies and salt spray testing (ASTM B117) indicate substantial enhancement of corrosion resistance in LSP-treated AZ31. The underlying reasons behind improved corrosion resistance of the LSP-AZ31 surface have been studied through detailed microstructural characterization and chemical analysis by SEM, TEM, and XPS. Formation of a ∼0.5 μm thick mixed metal (Mg, Al) oxide surface film, together with refinement in the size and number density of Al-Mn intermetallic particles, are shown to play a major role toward improved corrosion resistance after LSP treatment of the AZ31 alloy.
Compositional Fractioning
In article number 2302177, Lance Hubbard and co‐workers present an initial look at correlating the optical emissions of the weld plasma to that of the composition of ...particles condensed from the plasma plume. Particles removed from the melt pool through the plasma plume have atomic percent level differences in composition of alloy elements when compared to the originating metal.
Control of multicomponent alloys during welding is challenging because it lacks a real‐time understanding of composition. The optical emissions of plasma formed during laser‐induced metal welding ...correlate with the composition of particles ejected from the melt pool. Plasma emissions observed in this study contain large iron, manganese, chrome, and copper signatures, which match the composition of emitted particles. Particles recovered closest to the melt pool exhibit a core–shell morphology that is composed of iron‐manganese‐chrome intermetallic cores within copper shells. Particles collected farther from the melt pool, do not share this core–shell morphology, though similar elemental compositions are observed. The correlation between plasma optical emissions and particle composition can be used to predict the composition of the melt pool, allowing for real‐time welding and sintering control.
This work presents an initial look at correlating the optical emissions of the weld plasma to that of the composition of particles condesned from the plasma plume. Particles removed from the melt pool through the plasma plume have atomic percent level differences in composition of alloy elements when compared to the originating metal.
Metastable orientation relationships (ORs) between Cu and Cr are stabilized via epitaxial thin film deposition, with the initial layer of Cu(001) or Cr(001) grown epitaxially on MgO(001). The Bain OR ...is observed by x-ray diffraction and scanning/transmission electron microscopy for Cu(001) / Cr(001). In contrast, three Cr/Cu ORs are found for Cr deposition on Cu(001): the Pitsch OR, and two previously unreported ORs related to the Bain and Pitsch ORs, respectively. Ab initio calculations predict the energetics of these metastable ORs, and reveal that the deformation resistance of Cr makes the Bain OR energetically unfavorable when Cr films are deposited on Cu(001). These results show that kinetic constraints imposed by controlling the substrate surface and deposition conditions can lead to metastable interfacial structures.
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