Mechanism of destruction of the Al–Al4C3–Al2O3 alumo-matrix dispersion-hardened composite material with a layered structure on static and shock loading

Alumo-matrix dispersion-hardened composite materials are widely used in engineering due to the combination of high strength and low density, allowing the production of lightweight endurable structural elements for various purposes. They are used for manufacturing abrasive, triboengineering products, parts of the internal combustion engine cylinder-piston group, airframe and other special products. The paper is aimed to study the fracture mechanism of a layered dispersion-hardened Al–Al2O3–Al4C3 composite on static loading and impact. Specimens were obtained by liquid phase sintering of PAP-2 powder blanks in a vacuum. The liquid phase was formed due to Al–Al4C3 eutectic melt. The layered structure appeared due to the liquid-phase splicing of PAP-2 scaly particles along the contacting planes. Dispersion hardening of aluminum matrix was achieved due to nanosized lamellar alumocarbide crystals precipitated from the eutectic melt on cooling. The synthesis of alumina crystals – δ-Al2O3 – occurred due to the interaction of aluminum with residual oxygen molecules of the air on sintering at the furnace rarefaction of 10–5 mm Hg. The stable destruction of samples by the «shear stratification» mechanism was found to occur under static loading accompanied by the formation of cavities due to tearing of layered blocks under the action of shear stresses (σb = 430÷500 MPa, K1s = 14.0÷ ÷15.5 MPa·m1/2) At shock loading, a significant amount of material is involved in the fracture accompanied by the formation of cleavage steps between layered blocks and extended regions of ductile fracture dimples. Thanks to this mechanism, a high KCU (1.1·105 J/m2) is achieved comparable with that of the VT-5L titanium alloy. The developed composite can be used for manufacturing lightweight structural elements operated under dynamic loading.

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Effect of small alloying additions on mechanical properties of sintered Al—Sn composites

Deformation and Fracture of Materials ◽

10.31044/1814-4632-2021-11-2-9 ◽

2021 ◽

pp. 2-9

Author(s):

N. M. Rusin ◽

◽

A. L. Skorentsev ◽

Keyword(s):

Mechanical Properties ◽

Liquid Phase ◽

Equal Channel Angular Pressing ◽

Aluminum Matrix ◽

Liquid Phase Sintering ◽

Plastic Properties ◽

Aluminum Powders ◽

Alloying Additions ◽

Angular Pressing ◽

Alloying Additives

Composites of the Al—Sn system obtained by liquid-phase sintering of a mixture of doped aluminum powders with tin powder have been investigated. It was found that a small amount of alloying additives (Zn, Mg, Si, Cu) contributed to a considerable strengthening of the aluminum matrix when processing it by the method of equal channel angular pressing, but at the same time reduced the plastic properties. Samples alloyed with 2% Cu demonstrate the maximum strength and minimum ductility.

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Microstructure and Properties of In Situ Fabricated Al-5wt.%Si-Al2O3 Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.567.15 ◽

2012 ◽

Vol 567 ◽

pp. 15-20 ◽

Cited By ~ 3

Author(s):

Ling Cheng ◽

De Gui Zhu ◽

Ying Gao ◽

Wei Li ◽

Bo Wang

Keyword(s):

Shear Strength ◽

Liquid Phase ◽

Solid Phase ◽

Hold Time ◽

Aluminum Matrix ◽

Liquid Phase Sintering ◽

Aluminum Matrix Composites ◽

Matrix Composites ◽

X Ray

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.

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Mechanical properties of Al-Cu/B4C and Al-Mg/B4C metal matrix composites

Materials Testing ◽

10.1515/mt-2020-0052 ◽

2021 ◽

Vol 63 (4) ◽

pp. 350-355

Author(s):

Mehmet Ayvaz ◽

Hakan Cetinel

Keyword(s):

Mechanical Properties ◽

Powder Metallurgy ◽

Liquid Phase ◽

Oxide Layer ◽

Solid Phase ◽

Aluminum Matrix ◽

Liquid Phase Sintering ◽

Aluminum Matrix Composites ◽

Powder Metallurgy Method ◽

Matrix Composites

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.

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Synergetic Effect of Discontinuous Carbon Fibers and Graphite Flakes on Thermo-Mechanical Properties of Aluminum Matrix Composites Fabricated by Solid–Liquid Phase Sintering

Metals and Materials International ◽

10.1007/s12540-019-00324-0 ◽

2019 ◽

Vol 26 (2) ◽

pp. 155-167 ◽

Cited By ~ 1

Author(s):

Nabil Chamroune ◽

Florence Delange ◽

Nathalie Caillault ◽

Fabrice Morvan ◽

Yongfeng Lu ◽

...

Keyword(s):

Mechanical Properties ◽

Liquid Phase ◽

Carbon Fibers ◽

Synergetic Effect ◽

Aluminum Matrix ◽

Liquid Phase Sintering ◽

Aluminum Matrix Composites ◽

Matrix Composites ◽

Solid Liquid

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MACROSTRUCTURE AND STRENGTH OF AL–ZN–SN COMPOSITE PRODUCED BY LIQUID PHASE SINTERING OF AL–ZN ALLOY AND PURE TIN POWDER MIXTURE

Izvestiya Vuzov Poroshkovaya Metallurgiya i Funktsional’nye Pokrytiya (Universitiesʹ Proceedings Powder Metallurgy аnd Functional Coatings) ◽

10.17073/1997-308x-2018-2-69-75 ◽

2018 ◽

pp. 69-75

Author(s):

N. M. Rusin ◽

A. L. Skorentsev

Keyword(s):

Liquid Phase ◽

Powder Mixture ◽

Sintering Temperature ◽

Pure Aluminum ◽

Aluminum Matrix ◽

Liquid Phase Sintering ◽

Holding Time ◽

Vacuum Furnace ◽

Residual Pressure ◽

Localized Deformation

The paper studies the liquid phase sintering features of compacts made of Al–10Zn alloy and Grade PO 2 tin powder mixture as well as the effect of sintering modes on the structure and strength of the (Al–10Zn)–40Sn antifriction composite formed. The porosity of original raw compacts ranged from 5 to 18 %. They were sintered in a vacuum furnace at a residual pressure of gases lower than 10–2 MPa. Sintering temperature varied from 550 to 615 °С, where partial aluminum wetting with liquid tin was observed. Sample holding time at a given sintering temperature was 30–180 min. Structural studies have shown that the particle size of aluminum and tin phases increased with an increase in sintering temperature and holding time. Mechanical properties of sintered composites were determined by the compression test. Test samples were cut from the middle area of sintered compacts. The tests have shown that (Al–10Zn)–40Sn composite samples have high ductility. Moreover, these samples exhibit higher strength in comparison with Al–40Sn sintered composite with a pure aluminum matrix due to more intensive strain hardening of the matrix at high deformation levels. It was found that the composites obtained when sintering samples with a low initial porosity and subjected to pre-exposure at low temperature have the highest strength. Based on the reported results it can be concluded that the liquid-phase sintering method within the specified temperature range allows to obtain the (Al–10Zn)–40Sn composites with a continuous aluminum matrix to effectively prevent localized deformation in the soft Sn interlayers. The optimum sintering temperature should not exceed 600 °С.

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Effect of furnace atmosphere and silica content on the consolidation behaviour of magnesia partially stabilised zirconia

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178410 ◽

1990 ◽

Vol 48 (4) ◽

pp. 1056-1057

Author(s):

J. Drennan ◽

R.H.J. Hannink ◽

D.R. Clarke ◽

T.M. Shaw

Keyword(s):

Liquid Phase ◽

Silica Content ◽

Liquid Phase Sintering ◽

Furnace Atmosphere ◽

Boundary Phase ◽

Analytical Electron ◽

Analytical Electron Microscope ◽

Series Of Experiments ◽

Compositional Gradients ◽

Mobile Liquid

Magnesia partially stabilised zirconia (Mg-PSZ) ceramics are renowned for their excellent nechanical properties. These are effected by processing conditions and purity of starting materials. It has been previously shown that small additions of strontia (SrO) have the effect of removing the major contaminant, silica (SiO2).The mechanism by which this occurs is not fully understood but the strontia appears to form a very mobile liquid phase at the grain boundaries. As the sintering reaches the final stages the liquid phase is expelled to the surface of the ceramic. A series of experiments, to examine the behaviour of the liquid grain boundary phase, were designed to produce compositional gradients across the ceramic bodies. To achieve this, changes in both silica content and furnace atmosphere were implemented. Analytical electron microscope techniques were used to monitor the form and composition of the phases developed. This paper describes the results of our investigation and the presentation will discuss the work with reference to liquid phase sintering of ceramics in general.

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Microstructure and microanalysis of sintered Fe-Nd-B permanent magnets

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100178082 ◽

1990 ◽

Vol 48 (4) ◽

pp. 990-991

Author(s):

Mahesh Chandramouli

Keyword(s):

Electron Microscope ◽

Liquid Phase ◽

Permanent Magnets ◽

Phase Distribution ◽

Energy Dispersive Spectrometer ◽

Nucleation And Growth ◽

Liquid Phase Sintering ◽

Domain Wall Energy ◽

Oxide Phases ◽

Scanning Electron

Magnetization reversal in sintered Fe-Nd-B, a complex, multiphase material, occurs by nucleation and growth of reverse domains making the isolation of the ferromagnetic Fe14Nd2B grains by other nonmagnetic phases crucial. The magnets used in this study were slightly rich in Nd (in comparison to Fe14Nd2B) to promote the formation of Nd-oxides at multigrain junctions and incorporated Dy80Al20 as a liquid phase sintering addition. Dy has been shown to increase the domain wall energy thus making nucleation more difficult while Al is thought to improve the wettability of the Nd-oxide phases.Bulk polished samples were examined in a JEOL 35CF scanning electron microscope (SEM) operated at 30keV equipped with a Be window energy dispersive spectrometer (EDS) detector in order to determine the phase distribution.

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