Secondary phases and interfaces in a nitrogen-atmosphere sintered Al alloy: Transmission electron microscopy evidence for the formation of AlN during liquid phase sintering

Yan, Ming; Schaffer, G. B.; Qian, Ma

doi:10.1016/j.actamat.2010.06.041

Cited by 15 publications

(12 citation statements)

References 16 publications

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“…PM Al alloys are sintered commercially in nitrogen or nitrogen-rich atmospheres because of the enhanced sintering by nitrogen [20][21][22] caused by the formation of AlN during the liquid-phase sintering process. [23] This work presents a detailed study of the effect of the gas flow pattern in relation to the sample position on the surface and/or near-surface porosity of a 7xxx aluminum alloy Al-7Zn-2.5Mg-1Cu with the assistance of CFD modeling.…”

Section: Introductionmentioning

confidence: 99%

The Effects of Sample Position and Gas Flow Pattern on the Sintering of a 7xxx Aluminum Alloy

Yuan

Aminossadati

Huo

et al. 2012

Metall Mater Trans A

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The effects of sample position and gas flow pattern on the sintering of a 7xxx aluminum alloy Al-7Zn-2.5Mg-1Cu in flowing nitrogen have been investigated both experimentally and numerically. The near-surface pore distribution and sintered density of the samples show a strong dependency on the sample separation distance over the range from 2 mm to 40 mm. The open porosity in each sample increases with increasing separation distance while the closed porosity remains essentially unchanged. A two-dimensional computational fluid dynamics (CFD) model has been developed to analyze the gas flow behavior near the sample surfaces during isothermal sintering. The streamlines, velocity profile, and volume flow rate in the cavity between each two samples are presented as a function of the sample separation distance at a fixed nitrogen flow rate of 6 L/min. The CFD modeling results provide essential details for understanding the near-surface pore distribution and density of the sintered samples. It is proposed that the different gas flow patterns near the sample surfaces result in variations of the oxygen content from the incoming nitrogen flow in the local sintering atmosphere, which affects the self-gettering process of the aluminum compacts during sintering. This leads to the development of different near-surface pore distributions and sintered densities.

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Section: Introductionmentioning

confidence: 99%

The Effects of Sample Position and Gas Flow Pattern on the Sintering of a 7xxx Aluminum Alloy

Yuan

Aminossadati

Huo

et al. 2012

Metall Mater Trans A

Self Cite

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“…From all thermogravimetry curve after 400C goes up, this indicates there is gaining mass in sample. This is assumed to be a reaction between magnesium-aluminum oxide to form spinel and nitrogen gas-aluminum to form AlN [16]. Differential scanning calorimetry of powders are similar, this means lubricants does not effect on thermal behavior of Al-Si-SiC powder.…”

Section: Resultsmentioning

confidence: 99%

Effects of solid lubricants on properties of Al-Si-SiC composite powder produced by gas atomization technique

et al. 2020

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Al-Si-SiC composites powder was analyzed in this research. The powder was made by gas atomizing process. Powder characterization was done to observe its morphology, particle size distribution and thermal properties. Effects of lubricants were intensively investigated in this research with compositions and pressure variables. It is assumed that higher amount of solid lubricant put into the powder, the lower ejection force needed to take out compacted powder. Finding appropriate solid lubricant is necessary to improve green and sintering properties. EBS (ethylene bis stearamide), aluminum stearate, zinc stearate and paraffin wax were used for investigation. Sintering under ultra high purity nitrogen gas 99.9999% was carried out to produce high density material. SEM-EDS and XRD were carried to characterize this powder. SiC particles in this powder prohibit to achieve optimum sintering properties of Al-Si-SiC due to their resistance during compaction which leads to form pores and lower sintering density. And ethylene bis stearamide (EBS) seems to be suitable solid lubricant for this powder by giving lower ejection force, flowability and higher sintering density for 93.5%.

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“…This is a strongly exothermic reaction. The heat released may cause local melting, which will be conducive to sintering [28].…”

Section: Effect Of Sintering Temperature On Densificationmentioning

confidence: 99%

Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

Yuan

Yin

et al. 2021

Metals

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This present work investigates the effects of sintering temperature on densification, mechanical properties and microstructure of Al-based alloy pressed by high-velocity compaction. The green samples were heated under the flow of high pure (99.99 wt%) N2. The heating rate was 4 °C/min before 315 °C. For reducing the residual stress, the samples were isothermally held for one h. Then, the specimens were respectively heated at the rate of 10 °C/min to the temperature between 540 °C and 700 °C, held for one h, and then furnace-cooled to the room temperature. Results indicate that when the sintered temperature was 640 °C, both the sintered density and mechanical properties was optimum. Differential Scanning Calorimetry, X-ray diffraction of sintered samples, Scanning Electron Microscopy, Energy Dispersive Spectroscopy, and Transmission Electron Microscope were used to analyse the microstructure and phases.

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Secondary phases and interfaces in a nitrogen-atmosphere sintered Al alloy: Transmission electron microscopy evidence for the formation of AlN during liquid phase sintering

Cited by 15 publications

References 16 publications

The Effects of Sample Position and Gas Flow Pattern on the Sintering of a 7xxx Aluminum Alloy

The Effects of Sample Position and Gas Flow Pattern on the Sintering of a 7xxx Aluminum Alloy

Effects of solid lubricants on properties of Al-Si-SiC composite powder produced by gas atomization technique

Effects of Sintering Temperature on Densification, Microstructure and Mechanical Properties of Al-Based Alloy by High-Velocity Compaction

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