Effect of grain and secondary phase morphologies in the mechanical and damping behavior of Al7075 alloys

Puga, Hélder; Carneiro, V.H.; Barbosa, J.; Soares, Delfim

doi:10.1007/s12540-016-6073-y

Cited by 26 publications

(13 citation statements)

References 30 publications

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“…The overall equipment was prepared to be lowered and positioned into a resistance furnace holding a 1 L SiC crucible. This technique and configuration are designed to not only disperse the m-SiCp, but also to simultaneously promote melt treatment through physical processing (e.g., degassing, grain refinement, and secondary phase modification) [22][23][24][25]. For tests resorting only to mechanical stirring, the following protocol was adopted ( Figure 2b): (i) Axial (50 mm, full range up-down) movement with a 10 s period (5 mm/s) and (ii) translational motion with a 25 mm radius with a 20 rpm counterclockwise movement (~52 mm/s).…”

Section: Ultrasonic Melt Stirring For Microparticles Dispersionmentioning

confidence: 99%

Effect of Hybrid Ultrasonic and Mechanical Stirring on the Distribution of m-SiCp in A356 Alloy

Grilo

Puga

Carneiro

et al. 2020

Metals

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The present study details the micro-scale silicon carbide particle (m-SiCp) homogeneous distribution in an A356 alloy through hybrid ultrasonic-stirring melt treatment under different operation conditions. Ultrasonically excited fluids were studied by particle image velocimetry to estimate the efficiency of the acoustic streaming in different distances to the sonotrode. Distinct particle approaches to introduce the melt and stirring techniques were performed to determine a successful route to promote a homogenous distribution of reinforcement particles. Results showed that the addition of m-SiCp in the semisolid state significantly improved particle wettability, preventing rapid sedimentation. The combination of ultrasonic induced streaming and mechanical stirring is an effective tool for the homogeneous distribution of m-SiCp along the casting specimen.

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Section: Ultrasonic Melt Stirring For Microparticles Dispersionmentioning

confidence: 99%

Effect of Hybrid Ultrasonic and Mechanical Stirring on the Distribution of m-SiCp in A356 Alloy

Grilo

Puga

Carneiro

et al. 2020

Metals

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“…According to the Granato-Lücke theory [59], the strain independent internal friction (δ 0 ) is proportional to the dislocation density (ρ) and the mean length between weak pinning points (L d ) (Eq. ( 8)) [60]. The independent strain amplitude approach is applied in this study due to low stresses (σ Máx~3 0 MPa, by classic Timoshenko beam theory) generated by the hammer impact.…”

Section: Vibration Analysisdetermination Of Damping Ratiosmentioning

confidence: 99%

Heat treatment as a route to tailor the yield-damping properties in A356 alloys

Carneiro¹,

Puga²,

Meireles³

2018

Materials Science and Engineering: A

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A356 is a common industrial alloy due to its relatively good mechanical properties, reduced weight and capability be casted into complex structures. However, in order to display good static mechanical properties (e.g. elevated yield strength) it must be heat treated (usually T6), therefore, compromising its dynamic properties (e.g. damping ratio). This study analyses the role of such heat treatments in the overall microstructure of A356 poured in ceramic block, associating the morphology transformations with the internal mechanisms that enhance yield strength and reduce damping. It is suggested that these variables display an inverse proportionality and a linear model is determined for the design of alloys with tailored yield/damping by the use of different artificial ageing times. Methodology2.1. Alloy casting, heat treatment and sample production A356 alloy study was received in the form of 12.5 kg ingots with the chemical composition shown in Table 1. Melting of 0.3 kg of alloy was

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“…Some of these issues may be addressed by metal casting techniques, where there have been recent advances on the filling of thin-walled molds 45 allowing good dimensional control 46 – 50 coupled with good microstructural control 51 – 53 . However, the main difficulties associated with casting techniques are frequently related to mold production 54 .…”

Section: Introductionmentioning

confidence: 99%

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

Carneiro

Rawson

Puga

et al. 2021

Sci Rep

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Cellular materials are recognized for their high specific mechanical properties, making them desirable in ultra-lightweight applications. Periodic lattices have tunable properties and may be manufactured by metallic additive manufacturing (AM) techniques. However, AM can lead to issues with un-melted powder, macro/micro porosity, dimensional control and heterogeneous microstructures. This study overcomes these problems through a novel technique, combining additive manufacturing and investment casting to produce detailed investment cast lattice structures. Fused filament fabrication is used to fabricate a pattern used as the mold for the investment casting of aluminium A356 alloy into high-conformity thin-ribbed (~ 0.6 mm thickness) scaffolds. X-ray micro-computed tomography (CT) is used to characterize macro- and meso-scale defects. Optical and scanning electron (SEM) microscopies are used to characterize the microstructure of the cast structures. Slight dimensional (macroscale) variations originate from the 3D printing of the pattern. At the mesoscale, the casting process introduces very fine (~ 3 µm) porosity, along with small numbers of (~ 25 µm) gas entrapment defects in the horizontal struts. At a microstructural level, both the (~ 70 μm) globular/dendritic grains and secondary phases show no significant variations across the lattices. This method is a promising alternative means for producing highly detailed non-stochastic metallic cellular lattices and offers scope for further improvement through refinement of filament fabrication.

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Effect of grain and secondary phase morphologies in the mechanical and damping behavior of Al7075 alloys

Cited by 26 publications

References 30 publications

Effect of Hybrid Ultrasonic and Mechanical Stirring on the Distribution of m-SiCp in A356 Alloy

Effect of Hybrid Ultrasonic and Mechanical Stirring on the Distribution of m-SiCp in A356 Alloy

Heat treatment as a route to tailor the yield-damping properties in A356 alloys

Macro-, meso- and microstructural characterization of metallic lattice structures manufactured by additive manufacturing assisted investment casting

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