Microstructural analysis of a carbon fibre reinforced AZ91D magnesium alloy composite

Abstract

Interfacial regions in metal matrix composites are important in controlling the mechanical and thermal properties of these materials. An ultrahigh modulus fibre-reinforced magnesium alloy matrix composite has been studied, with particular attention paid to the interfacial and precipitate microstructures. Fibres were surface treated but uncoated prior to composite manufacture. Observations revealed that an interface consisting of polycrystalline magnesium oxide with occasional Mg 17 Al 12 (b) precipitate particles predominates. Discontinuous b particles formed at fibre surfaces, and continuous spherical and lamellar b precipitates nucleated at grain boundaries and fibre surfaces. High dislocation densities exist at the interface indicating matrix-yielding subsequent to manufacture and that a high mean residual compressive stress acts on fibres. The effect that the observed microstructural features has on composite properties and on interfacial bonding is discussed and compared to examples in the literature.

Enhanced ductility of Mg–3Al–1Zn alloy reinforced with short length multi-walled carbon nanotubes using a powder metallurgy method

“…Thus, CNTs particles prevent the production of β phases, as evident from XRD results. Numerous investigators reported the formation of carbide, Al 4 C 3 [26] and Al 2 MgC 2 [27]. In order to confirm the carbide formation, transmission electron microscopy (TEM) was carried for Mg3Al-1Zn-1.0CNTs composite as shown in Fig.…”

Multi-walled carbon nanotube-reinforced magnesium alloy composites

“…The interfacial state between magnesium alloy and carbon nanotubes was also considered, because the formation of carbide (Al 2 MgC 2 ) was reported when the temperature was >773 K and the aluminum level in magnesium alloy compositions was >0.6 % and <19 % [25].…”

Constitutive behavior of Csf/AZ91D composites compressed at elevated temperature and containing a small fraction of liquid

“…According to the phase diagram of alloy AZ91D, the main constituents of the matrix alloy are the primary solid solution (a-Mg) and lamellar eutectic (constituted by a-Mg and b-Mg 17 Al 12 ). The interfacial region includes the precipitated phase (b-Mg 17 Al 12 ) and reactive phase (Al 4 C 3 ), which has been verified by SEM, EDS and TEM in literatures [27,28]. The endothermic peak at low temperature on the heat flow curve (in Fig.…”