Compression deformation behaviour of aluminium matrix syntactic foams under quasistatic loading: in situ SEM compressive tests

SiCp reinforced aluminium matrix composites (AMCs), which are widely used in the aerospace, automotive, and electronic packaging fields along with others, are usually prepared by ex situ techniques. However, interfacial contamination and poor wettability of the ex situ techniques make further improvement in their comprehensive performance difficult. In this paper, SiCp reinforced AMCs with theoretical volume fractions of 15, 20, and 30% are prepared by powder metallurgy and in situ reaction via an Al-Si-C system. Moreover, a combined method of external addition and an in situ method is used to investigate the synergistic effect of ex situ and in situ SiCp on AMCs. SiC particles can be formed by an indirect reaction: 4Al + 3C → Al4C3 and Al4C3 + 3Si → 3SiC + 4Al. This reaction is mainly through the diffusion of Si, in which Si diffuses around Al4C3 and then reacts with Al4C3 to form SiCp. The in situ SiC particles have a smooth boundary, and the particle size is approximately 1–3 μm. A core-shell structure having good bonding with an aluminium matrix was generated, which consists of an ex situ SiC core and an in situ SiC shell with a thickness of 1–5 μm. The yield strength and ultimate tensile strength of in situ SiCp reinforced AMCs can be significantly increased with a constant ductility by adding 5% ex situ SiCp for Al-28Si-7C. The graphite particle size has a significant effect on the properties of the alloy. A criterion to determine whether Al4C3 is a complete reaction is achieved, and the forming mechanism of the core-shell structure is analysed.

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Investigation of the adhesion strength and deformation behaviour of in situ fabricated NbC coatings by scratch testing

Surface and Coatings Technology ◽

10.1016/j.surfcoat.2016.05.004 ◽

2016 ◽

Vol 299 ◽

pp. 135-142 ◽

Cited By ~ 27

Author(s):

Xiaolong Cai ◽

Yunhua Xu ◽

Nana Zhao ◽

Lisheng Zhong ◽

Ziyuan Zhao ◽

...

Keyword(s):

Adhesion Strength ◽

Deformation Behaviour ◽

Scratch Testing ◽

Strength And Deformation

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Investigation of Small- to Large-Strain Moduli Correlations of Rockfill Materials – Application to Romaine-2 Dam

Canadian Geotechnical Journal ◽

10.1139/cgj-2021-0113 ◽

2021 ◽

Author(s):

Ibrahim Lashin ◽

Michael Ghali ◽

Marc Smith ◽

Daniel Verret ◽

Mourad Karray

Keyword(s):

Large Strain ◽

Deformation Behaviour ◽

Numerical Data ◽

Small Strain ◽

Hyperbolic Model ◽

Large Strains ◽

Initial Modulus ◽

Rockfill Materials ◽

Materials Used

Establishment of a relationship between the shear wave velocity (Vs) and other geotechnical parameters of rockfill soils at large strains (oedometer modulus, Moedo, tangent modulus, Et) is considered a significant step towards more precise modelling of earth-structure deformation behaviour. In this study, four samples of different gradations, reconstituted from the rockfill materials used in the construction of the Romaine-2 dam, were experimented to correlate the small strain to large strain moduli. Development of Moedo and Vs with consolidation was measured in the laboratory using the piezoelectric ring-actuator technique (P-RAT) incorporated in a large oedometer. Therefore, a correlation between Moedo and small strain shear modulus Go was proposed. Moreover, numerical simulations were performed based on the Duncan-Chang hyperbolic model to correlate the Vs to Duncan-Chang initial modulus(Ei). Based on the experimental and numerical data, a relation between Ei and Vs of the tested rockfill has been established. Verification studies were also carried out on in-situ measurements during Romaine-2 dam construction, proofing the ability of the proposed relationships to predict Ei related to the minor principal stress (σ3) from in-situ Vs measurement. The proposed correlations could help the geotechnical designers to estimate accurately the deformation of rockfill materials from in-situ Vs measurement.

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Characterisation of Aluminium Matrix Syntactic Foams under Static and Dynamic Loading

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.82.142 ◽

2011 ◽

Vol 82 ◽

pp. 142-147 ◽

Cited By ~ 2

Author(s):

Mohamed Altenaiji ◽

Graham K. Schleyer ◽

Yo Yang Zhao

Keyword(s):

Compressive Strength ◽

Porous Ceramic ◽

Syntactic Foam ◽

Absorption Capacity ◽

Core Material ◽

Aluminium Matrix ◽

Test Machine ◽

Syntactic Foams ◽

Pressure Infiltration ◽

Energy Absorbing

Development of a lightweight, strong and energy-absorbing material that has potential application for the protection of vehicles and occupants against impact and blast, is a difficult challenge facing the materials community. Aluminium matrix syntactic foams will be investigated as a possible core material as part of a multi-layered protection system for military vehicles. Aluminium matrix syntactic foams are composite materials consisting of an aluminium matrix implanted with hollow or porous ceramic particles. This paper investigates the mechanical properties of aluminium matrix syntactic foam with different sizes of ceramic micro-spheres and different grades of aluminium, fabricated by the pressure infiltration method. The static crushing behaviour of the foam was investigated under two test conditions using an Instron 4505 machine. Results are compared and discussed. The dynamic compressive response was investigated using a drop-weight impact test machine. It was found that the particle size of the ceramic micro-spheres and the grade of the aluminium metal have a significant effect on the energy absorption capacity of the material. The compressive strength of the syntactic foam was found to increase with increasing compressive strength of the metal matrix.

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