Nitridation reactions of molten Al-(Mg, Si) alloys

Scholz, H.; Greil, Peter

doi:10.1007/bf00588302

Cited by 94 publications

(55 citation statements)

References 12 publications

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“…One of the solutions to this problem is to use a binary melt containing Al 25) instead of a pure Al melt. Si has a much higher melting point (1414°C) and lower heat of nitridation (¦H 298K = ¹246 kJ mol ¹1 , as calculated using the FACT-Web program) than Al.…”

Section: ¹1mentioning

confidence: 99%

Synthesis of AlN needles by nitridation of Al–Si melt

Kobayashi

Fukutomi

Takagi

2016

J. Ceram. Soc. Japan

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Needle-like single crystals of aluminum nitride (AlN) were synthesized by the direct nitridation of an AlSi binary melt. The growth behavior and shape of the needles were changed by varying the Al:Si ratio. With lower Al content, needles with high aspect ratio (>20) preferentially grew on the AlSi melt and crucible wall. With increasing Al content, needles with lower aspect ratios having various shapes such as ribbon-like and bended shapes tended to grow. The longer directions of the needles could mainly correspond to the c-axis of a wurtzite-type AlN.©2016 The Ceramic Society of Japan. All rights reserved.Key-words : Aluminum nitride, Whisker, Growth from melt, Single crystal [Received May 26, 2016; Accepted August 5, 2016] Aluminum nitride (AlN) has high refractoriness, high hardness, high thermal conductivity, good corrosion resistance, and good insulation property. 1),2) AlN ceramics have been widely used as substrates and structural components for semiconductor devices and manufacturing. AlN is a typical sintering-resistant material; therefore, high-temperature sintering with sintering additives is necessary to obtain dense AlN samples. Rare-earth and alkaliearth oxides such as Y 2 O 3 and CaO have been found to be effective for developing dense AlN ceramics with high thermal conductivity. 3)9)The growth of AlN single crystals and thin films is another important area of research. AlN single crystals have been used in substrates and buffer layers in the growth process of GaN and AlGaN. 10)13) AlN also has attracted attention for use in widebandgap devices such as a deep ultraviolet light-emitting diode (UV-LEDs).14) In addition, AlN single crystals with needle or whisker shapes are used as seed crystals in the growth of largesized AlN single crystals, 15) has been studied. The direct nitridation of Al is a simple process for obtaining large-sized AlN crystals at relatively low temperatures. In this process, the crystal tends to have a needle-like shape from 1800 to 1900°C and a platelet-like shape at higher temperatures. 20) However, the low melting point (660°C) and high heat of nitridation (¦H 298K = ¹318 kJ mol ¹1, as calculated using the FACT-Web program) of Al often make the evaporation and nitridation rate of Al uncontrollable; this limits the ability to control the morphology of AlN crystals by the growth temperature alone. One of the solutions to this problem is to use a binary melt containing Al 25) instead of a pure Al melt. Si has a much higher melting point (1414°C) and lower heat of nitridation (¦H 298K = ¹246 kJ mol ¹1 , as calculated using the FACT-Web program) than Al. Therefore, the morphology of AlN can be controlled by changing the Al:Si ratio in the AlSi melt. In this study, we synthesized needle-like AlN crystals by the direct nitridation of an AlSi binary melt with various Al:Si ratios.Commercially available Al powder (Rare Metallic Co., Ltd., 99.9%) and Si powder (Rare Metallic Co., Ltd., 99.9%) were used for raw powders. These powders were weighted with Al:Si molar ratios of 1:3, ...

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Section: ¹1mentioning

confidence: 99%

Synthesis of AlN needles by nitridation of Al–Si melt

Kobayashi

Fukutomi

Takagi

2016

J. Ceram. Soc. Japan

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“…1 However, AMCs manufactured by conventional ex situ processes are economically unfavorable due to expensive reinforcing materials and thermodynamic instability resulting from interfacial reaction between matrix and reinforcements. 2 Thus, in situ fabrication of AMCs with a ceramic second phase such as TiC, Al 2 O 3 , and SiC has been investigated for several decades and various processes like self-propagating high temperature synthesis, 3 directed melt oxidation, 4,5 or gas bubbling method 2,[6][7][8][9][10] have been developed as a feasible process depending on the formation of ceramic second phase. Recently, aluminum nitride (AlN) has been considered as an attractive second phase in AMCs due to excellent TC and low CTE.…”

Section: Introductionmentioning

confidence: 99%

“…[10][11][12][13][14] Thus, a few scenarios have been proposed to fabricate in situ AMCs with AlN by nitridation of Al melt by gas-melt reaction. 5,10 For…”

Section: Introductionmentioning

confidence: 99%

“…example, as a directed melt nitridation process, 5 molten Al-(Mg, Si) alloys were heated above 1273 K and held for more than 12 h in nitrogen atmosphere, which promoted the formation of microporous AlN on the surface of molten alloy and outward growth of AlN by continuous wetting of the liquid alloy through the microchannel, resulting in the formation of AMCs with interconnected network of alloy and AlN. Although this process leads to the formation of AMCs with high volume fraction (V p ) of AlN above 50 vol%, TC of Al matrix abruptly deteriorates with the addition of alloying elements, Mg and Si.…”

Section: Introductionmentioning

confidence: 99%

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In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

Lee

Park

2016

J. Mater. Res.

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Our study proposes in situ synthesis of cold-rollable aluminum nitride (AlN) reinforced aluminum matrix composites with attractive thermal properties via arc plasma-induced accelerated volume nitridation (APAVN). Within three minutes of repeated APAVN using commercial nitrogen gas, volume fraction of AlN increased up to 40 vol%, which is the highest value ever reported by in situ nitridation of pure aluminum. The composites contained homogeneously dispersed AlN particulates with strong interfacial bonding and low interfacial thermal resistance, which resulted in unique combination of a relatively low coefficient of thermal expansion and high specific thermal conductivity. APAVN resulted from instantaneous chemisorption of dissociated nitrogen, enhanced diffusion of dissolved nitrogen, and improved wettability, which led to much more AlN formation, ;2.94 Â 10 À1 g/(min cm 3 ), which is about 400 times higher than that in the gas bubbling method. These results would ultimately give us a promising strategy for continuous production of in situ Al-AlN composites for heat sink applications through cost-effective processing.

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“…Magnesium has also been shown to increase AlN formation in powder compacts sintered in a nitrogen atmosphere [67], also suggesting that the magnesium exposes aluminium metal that is then able to react with the nitrogen. Experiments on synthesising AlN via direct nitridation of molten Al alloys have also shown that magnesium additions increase the conversion of Al to AlN [72,73].…”

Section: Magnesiummentioning

confidence: 99%

Sintering of an aluminium alloy under pressurised conditions

Bonner¹

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Nitridation reactions of molten Al-(Mg, Si) alloys

Cited by 94 publications

References 12 publications

Synthesis of AlN needles by nitridation of Al–Si melt

Synthesis of AlN needles by nitridation of Al–Si melt

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

Sintering of an aluminium alloy under pressurised conditions

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Nitridation reactions of molten Al-(Mg, Si) alloys

Cited by 94 publications

References 12 publications

Synthesis of AlN needles by nitridation of Al&ndash;Si melt

Synthesis of AlN needles by nitridation of Al&ndash;Si melt

In situ synthesis of cold-rollable aluminum–aluminum nitride composites via arc plasma-induced accelerated volume nitridation

Sintering of an aluminium alloy under pressurised conditions

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Synthesis of AlN needles by nitridation of Al–Si melt

Synthesis of AlN needles by nitridation of Al–Si melt