Aluminium matrix

Figure 13 SIMS plot of Na, Sn, Mg, and A1 concentrations as a function of time in graphite aluminium composite prepared by the sodium process. (Analysis starts in graphite fiber and proceeds into the aluminium matrix.) (From Ref. 75.)...

Roman, I. and Aharonov, R. (1992). Mechanical interogation of interfaces in monofilament model composites of continuous SiC fiber-aluminium matrix. Acta Metall. Mater. 40, 477-485. 

When a composite is subjected to external forces, the energy of the matrix is only transferred to the fibres when there is question of a proper attachment. For that reason fibres are some-times provided with a layer of another material. An example boron fibres in an aluminium matrix are provided with a silicon carbide coating and as a result the fibres are called borsic fibres. The thermal expansion coefficient of a fibre and its matrix must correspond. Figure 14.9 is a representation of what takes place when a crack in a fibre-reinforced matrix grows. 

Fig. 5.13. A micrograph of the transition zone between molybdenum and Mo-saturated liquid aluminium.309 Temperature 750°C, dipping time 1800 s. Inclusions in the aluminium matrix are crystals of MoA14 formed during cooling the aluminium melt.

Of 2.5 mass % Fe and 0.28 mass % Ni added initially to aluminium in order to obtain the saturated melt at 700°C, only 0.41 mass % (0.20 at.%) Fe and 0.05 mass % (0.03 at.%) Ni is retained in an aluminium solid solution during cooling down the aluminium melt. The remaining iron and nickel react with aluminium to form a eutectic and intermetallic grains distributed at random in the aluminium matrix. Microhardness, HV 50, was found to be 2.0 GPa for the Fe-Ni alloy base, 9.3 GPa for the intermetallic layer and 0.5 GPa for the aluminium matrix. The relative error of its measurement was around 10 %. 

Two intermetallic layers are observed in the transition zone between a 50 mass % Fe-50 mass % Ni alloy and the aluminium melt saturated with the alloy constituents (Fig. 5.16c). The layer adjacent to the alloy base is only about 8 pm thick and consists of the Fe2Al7 compound. The much thicker layer bordering with the aluminium matrix tends to destroy. The ternary FeNiAl9 compound is dominant in this layer. Its microhardness is 6.2 GPa. The microhardness of the alloy base is 2.1 GPa and that of the aluminium matrix is 0.7 GPa. 

A tendency to destroying becomes more pronounced in the case of an intermetallic layer between a 25 mass % Fe-75 mass % Ni alloy and the aluminium melt saturated with the alloy constituents (Fig. 5.16d). As seen, relatively large intermetallic grains were separated from the alloy base and passed into the liquid phase. Microhardness values are 2.3 GPa for the alloy base, 5.3 GPa for the intermetallic grains and 0.7 GPa for the aluminium matrix. 

Besides the FeNiAl9 compound layer, two more phases were revealed at the interface between a 25 mass % Fe-75 mass % Ni alloy and the saturated aluminium melt. At a smaller dipping time of 900 sec, cracking was not so pronounced as at 3600 sec, and the layers adjacent to the alloy base could readily be investigated by electron probe microanalysis. The first measurement was carried out at a distance of 2 pm away from the alloy-intermetallic interface, while the other measurements were made at a step of 2.5 pm towards the aluminium matrix. The following set of aluminium, iron and nickel contents (at.%) was obtained (Camebax SX50) ... 

Figure 3. Tensile flow curves of pure aluminium matrix composites, reinforced with angular (A) and polygonal (P) alumina particles (see Fig. 2), of diameter given in pm by the legend of the curves. The 10 and 5 pm angular particle reinforced composites fail before tensile instability is reached.

Figure 4. Tensile flow curves of two Al-4.5 wt.% Cu reinforced with aluminium matrix composites, reinforced with angular and polygonal alumina particles of roughly the same size. The data show the significant improvements brought by matrix alloying (see Fig. 3) as well as the strong influence of the ceramic particle type on the composite mechanical performance. With the stronger ceramic, the material features high strength and acceptable tensile ductility despite the fact that it is more than 50% ceramic.

Metzger, M., and S. G. Fishman. Corrosion of aluminium-matrix composites Status report. Ind. Eng. Chem. Prod. Res. Dev., 22 2986,... 

The diffusion coefficient of aluminium in a ferritic iron-aluminium matrix is some orders of magnitude higher than in austenitic Ni3Al. Because of the low diffusion coefficient, diffusion in nickel aluminides is slow and aluminium depletion beneath the alumina scale and formation of nonprotective nickel oxides has been observed in Ni3Al. [4]. 

Adeeyinwo and Tyson [10] used a stainless-steel disc filter with 2 m pore size, 6 mm diameter, and 2 mm thickness to separate calcium from an interfering aluminium matrix by oxalate precipitation. The results were inferior to those obtained using membrane filters, giving poor reproducibility. These results are consistent with the experiences of Valcarcel et al.[7] using disc type stainless-steel filters mentioned above. ... 

R. Sasikumar, R. M. Arunachalam, Synthesis of Nanostructured Aluminium Matrix Composite (AMC) through Machining. Materials Letters 2009, 63, 2426-2428. 

Kyono T et al. Study on compatibility between carbon fiber ( Torayca ) and aluminium matrix, 1st Japan International SAMPE Symposium and Exhibition, 964, Nov 28-Dec 1, 1989. 

Author Affiliation, Tsukuba, Nat, Inst. Materials Chem, Res Nikkei Techno-Research Co. Ltd, Mechanical properties and metallography of aluminium matrix composites reinforced by the Cu or Ni plating carbon multifilament, J Mater Res, 8(10), 2492-2498, 1993. 

Soni PR, Rajan TV, Ramakrishnan P, TensUe behaviour of carbon fibre reinforced aluminium matrix composites, Metals Mater Proc, 7(4), 267 273, 1996. 

A foreign technology that could be considered by CNEA is the melt-dilute process, provided it complies with the acceptance criteria applied to deep geological disposal. In this sense, the melt-dilute process should gain more evidence about the long term durability of the aluminium matrix in comparison to glass and ceramic matrices. 

Although there is still no general consensus of opinion, it does seem that hydrogen affects the plastic deformation properties of the aluminium matrix in the crack tip zones. 

Due to their high specific strength and stiffness, long-fibre reinforced aluminium matrix composites are attractive in aerospace apphcations. The high-gain antenna boom of the Hubble Space Telescope, for example, is made from a carbon-fibre reinforced aluminium matrix composite [114]. Aluminium oxide reinforced aluminium matrix composites are also suitable for push rods in motorcycle engines and for electrically conductive and mechanically loaded connectors on power poles [1]. 

Short-fibre reinforced metal matrix composites are significantly less expensive than long-fibre reinforced materials and can thus be used in automotive engineering or in sports equipment. For example, short-fibre reinforced aluminium-silicon carbide composites can be used as pistons in diesel engines at elevated temperatures [49]. Golf clubs and bicycle components can also be manufactured from aluminium matrix composites. Frequently, whiskers (see section 6.2.8) are used as short fibres because of their high strength and favourable aspect ratio. 

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