Fabrication of Al-AlN Nanocomposites

2016 ◽  
Vol 684 ◽  
pp. 302-309 ◽  
Author(s):  
Aleksandr P. Amosov ◽  
Y.V. Titova ◽  
I.Y. Timoshkin ◽  
Antonina A. Kuzina

A review of the methods of obtaining and properties of aluminum matrix composites, discretely reinforced with ceramic particles and nanoparticles of aluminum nitride AlN, is given. The survey shows that at low weight, nanocomposites Al-AlN possess improved physical and mechanical properties, including at high temperatures up to 400-550°C, which makes them very attractive for applications in automotive, aerospace and semiconductor technology. However, due to the long duration and energy consumption, expensive and complicated equipment, low productivity of existing solid-phase methods of powder metallurgy and liquid-phase metallurgical processes of fabrication of nanocomposites of Al-AlN, there are not yet the mastered technologies of industrial production of these composites. Azide technology of self-propagating high-temperature synthesis (SHS-AZ) using sodium azide NaN3 as a solid nitriding reagent allows you to get relatively inexpensive nanopowder of aluminum nitride in the form of nanofibers along with side salt of cryolite Na3AlF6, which can play the role of flux when working with molten aluminum. A new simple ex-situ method of introduction of AlN particles in the molten aluminum alloy in the form of a composite master alloy obtained by fusing together a flux carnallite KCl·MgCl2 with AlN nanopowder mixed with cryolite Na3AlF6 was proposed. Results of experiments on the application of the proposed method for obtaining nanocomposite with matrix made of aluminum-magnesium alloy AlMg6 containing up to 1 % of the reinforcing phase AlN are presented.

2016 ◽  
Vol 254 ◽  
pp. 110-115
Author(s):  
Mihai Ovidiu Cojocaru ◽  
Mihaela Raluca Condruz ◽  
Florică Tudose

In this paper was followed the processing flow of aluminum-alumina compositions (10÷20% alumina) in powder state, aiming to obtain aluminum matrix composites reinforced with alumina particles, starting from selecting and mixing the grading fraction of both components reaching up to sintering; it was analyzed the way in which reflects the variation of grading fraction ratio (expressed through average particle diameter in the analyzed fractions limits) on the level of technological interest features: apparent density, tapped density, flowability, presability and on densification after sintering (in various environments). By transmission electron microscopy was observed that aluminum particles showed on the surface a nanoscale oxide film, so the sintering occurs between congeneric areas – by solid phase sintering mechanisms [1, 2, 3]. The analysis of thermophysical properties revealed a decrease of thermal diffusivity at an increase of alumina, simultaneous with the decrease of the densification level.


2012 ◽  
Vol 567 ◽  
pp. 15-20 ◽  
Author(s):  
Ling Cheng ◽  
De Gui Zhu ◽  
Ying Gao ◽  
Wei Li ◽  
Bo Wang

Alumina reinforced aluminum matrix composites (Al-5wt.%Si-Al2O3) fabricated by powder metallurgy through hot isotactic pressing were sintered in different processes, i.e. solid and liquid phase sintering. Optical microscopy (OM), X-ray diffraction (XRD), scanning electron microscope (SEM), Energy Dispersive X-ray (EDX) techniques were used to characterize the sintered composites. The effects of solid phase and liquid phase sintering on density, microstructure, microhardness, compression and shear strength were investigated. It was found that in situ chemical reaction was completed in solid phase sintering, but the composites had lower microhardness, comprehension and shear strength due to low density and segregation of alumina and Si particles in microstructure. Segregation of reinforcement particles in solid phase sintering resulted from character of solid reaction and Si diffusion at high temperature over a long hold time.


2017 ◽  
Vol 62 (2) ◽  
pp. 1235-1242 ◽  
Author(s):  
A. Lekatou ◽  
N. Gkikas ◽  
A.E. Karantzalis ◽  
G. Kaptay ◽  
Z. Gacsi ◽  
...  

AbstractAluminum matrix composites were prepared by adding submicron sized WC particles into a melt of Al 1050 under mechanical stirring, with the scope to determine: (a) the most appropriate salt flux amongst KBF4, K2TiF6, K3AlF6and Na3AlF6for optimum particle wetting and distribution and (b) the maximum carbide volume fraction (CVF) for optimum response to sliding wear. The nature of the wetting agent notably affected particle incorporation, with K2TiF6providing the greatest particle insertion. A uniform aluminide (in-situ) and WC (ex-situ) particle distribution was attained. Two different sliding wear mechanisms were identified for low CVFs (≤1.5%), and high CVFs (2.0%), depending on the extent of particle agglomeration.


2021 ◽  
Vol 63 (4) ◽  
pp. 350-355
Author(s):  
Mehmet Ayvaz ◽  
Hakan Cetinel

Abstract To be able to successfully produce ceramic-reinforced aluminum matrix composites by using the powder metallurgy method, the wetting of ceramic reinforcements should be increased. In addition, the negative effects of the oxide layer of the aluminum matrix on sinterability should be minimized. In order to break the oxide layer, the deoxidation property of Mg can be used. Furthermore, by creating a liquid phase, both wettability and sinterability can be improved. In this study, the effects of Mg and Cu alloy elements and sintering phase on the wettability, sinterability, and mechanical properties of Al/B4C composites were investigated. For this purpose, various amounts (5, 10, 20, and 30 wt.-%) of B4C reinforced Al5Cu and Al5Mg matrix composites were produced by the powder metallurgy method. After pressing under 400 MPa pressure, composite samples were sintered for 4 hours. The sintering was carried out in two different groups as solid phase sintering at 560 °C and liquid phase sintering at 610 °C. Despite the deoxidation effect of Mg in Al5Mg matrix composites, higher mechanical properties were determined in Al5Cu composites which were sintered in liquid phase because wettability increased. The highest mechanical properties were obtained in the 20 wt.-% B4C reinforced Al5Cu sample sintered in liquid phase.


2013 ◽  
Vol 575-576 ◽  
pp. 179-182
Author(s):  
Hong Ming Wang ◽  
Guirong Li ◽  
Yun Cai ◽  
Yu Tao Zhao

The ZrB2 particulate reinforced aluminum matrix composites were fabricated via melt direct reaction method using Al-K2ZrF6-KBF4 components. 850°C and 30 min were the optimized synthesizing temperature and reaction time separately. The metallurgical thermodynamic and kinetic processes were then analyzed in detail. It reveals that the interphases include Al3Zr, AlB2, [Z and [ atoms. The ZrB2 particulates can be acquired through the molecular combination between Al3Zr and AlB2 or atomic combination between Zr and B atomics. The in situ reaction between reactive salts and molten aluminum takes place spontaneously, which exhibits the character of liquid-liquid reaction. Scanning electronic microscope observation results demonstrate that the sizes of ZrB2 particulates are almost 100-200 nm. The intervals between particles are almost 200-400 nm, demonstrating a unirom status of distribution.


2019 ◽  
Vol 141 (7) ◽  
Author(s):  
Santanu Sardar ◽  
Susanta Kumar Pradhan ◽  
Santanu Kumar Karmakar ◽  
Debdulal Das

Tribological characterizations of composites are primarily focused on the evaluation of wear resistance (WR) and/or the coefficient of friction, although roughness of abraded surfaces (RASs) is one of the key factors that also determines tribo-performances. This study is aimed at modeling RAS in conjunction with WR considering experimental results of Al-matrix/alumina composites performed under two-body abrasion following the central composite design method. Influences of different in situ and ex situ parameters on tribo-responses were analyzed and modeled using analysis of variance, the response surface method, and multi-response optimization. The WR of the selected system was maximized at around 15 wt% alumina at which RAS was also the highest. The positive role of reinforcement on WR and its adverse effect on RAS were explained by micro-mechanisms of abrasion.


10.30544/422 ◽  
2019 ◽  
Vol 25 (3) ◽  
pp. 195-208
Author(s):  
Nishith R Rathod ◽  
Jyoti Menghani

In the recent era, Metal Matrix Composites (MMCs) are one of the most vigorously studied topics in material science. Lightweight metals and its alloys create an intense attraction for tailoring new metal matrix composites to overcome conventional limitations like low strength. Aluminum metal matrix composites signify to the high-grade lightweight high-performance aluminum-based MMCs. The reinforcements in aluminum matrix composites could be in the form of particulates, whiskers, and continuous fiber or discontinuous fiber, where weight or volume fraction varies from a few percentages to 60%. Properties of aluminum metal matrix composites can be customized as per the demand of the industry by getting the appropriate combination of the metal matrix, reinforcements, and selective processing route. Nowadays many grads of aluminum matrix composites are fabricated by different routes where in situ route processing is more attractive compared with conventional ex-situ process because it delivers excellent wettability, thermally stability of reinforcements, the bonding strength between reinforcements and matrix, cohesive atomic structure, and fine grain size of reinforcements (specifically nano size). The devoted research work of aluminum matrix composites during the last three-decade generates a wealth of knowledge on the effect of reinforcements vis-à-vis mechanical, chemical, tribological properties of aluminum matrix composites. The acceptance of the aluminum matrix composites as engineering materials depends not only on the performance advantages of the composites, but it also depends upon the cheap, easy, and familiar fabrication technologies for these tailored materials.


2013 ◽  
Vol 850-851 ◽  
pp. 173-176 ◽  
Author(s):  
Jin Jin Yao ◽  
Di Chu ◽  
Yan Qiu Han ◽  
Li Hua Ben ◽  
Chun Jing Wu

The physical and mechanical properties that can be obtained with metal matrix composites (MMCs) have made them attractive candidate materials for aerospace, automotive and numerous other applications. In this paper, the current fabrication methods of continuous fiber reinforced aluminum matrix composites are briefly described.


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