Examinando por Autor "Hidalgo-Manrique, Paloma"

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Copper/graphene composites: a review
(Springer, 2019-06-11) Hidalgo-Manrique, Paloma; Lei, Xianzhang; Ruoyu, Xu; Mingyu, Zhou; Kinloch, Ian A; Young, Robert J
Recent research upon the incorporation of graphene into copper matrix composites is reviewed in detail. An extensive account is given of the large number of processing methods that can be employed to prepare copper/graphene composites along with a description of the microstructures that may be produced. Processing routes that have been employed are described including powder methods, electrochemical processing, chemical vapour deposition, layer-by-layer processing, liquid metal infiltration among a number of others. The mechanical properties of the composites are described in detail along with an account of the structural factors that control mechanical behaviour. The mechanics and mechanisms of deformation are discussed, and the effect of factors such as the graphene content and the type of graphene used, along with processing conditions for the fabrication of the composites, is described. The functional properties of copper/graphene composites are also reviewed including their electrical and thermal properties, and tribological and corrosion behaviour. In each case, the effect of the graphene type and content, and processing conditions are also described. Finally, possible future applications of copper/graphene composites are discussed.
Interaction between precipitate basal plates and tensile twins in magnesium alloys
(Springer, 2019-05-29) Hidalgo-Manrique, Paloma; Robson, Joseph D
A textured Mg-Al-Zn alloy rolled plate was solution-treated and then aged at 320 ºC for 2 h and 116 h, respectively. Afterwards, the three conditions were tested at room temperature in compression along the transverse direction to activate {101 ̅2} twinning. Both aged specimens exhibited a yield stress about 10 MPa higher than that of the solution-treated condition, with the increase of the yield stress attributed to the extra stress required for the twins to grow in the presence of particles. In order to understand the mechanism responsible for such strengthening, the effect of the precipitate basal plates on the critical resolved shear stress (CRSS) for twin growth was estimated using four different calculation approaches: Orowan stress to bow twinning dislocations around particles, elastic back-stress resulting from unsheared precipitates inside the twin, strengthening of basal slip within the twin (related to plastic relaxation), and stress to bow a twinning super-dislocation loop capable of further expansion. These methods give an order of magnitude difference in the calculated strengthening effect that spans the measured CRSS increase. The last two methods give the best estimates of the CRSS increase for twin growth, but none of them accounts perfectly for it.
Mg–1Zn–1Ca alloy for biomedical applications. Influence of the secondary phases on the mechanical and corrosion behaviour
(Elsevier, 2020-08-05) Pulido-González, Nuria; Torres, Belén; García-Rodríguez, Sonia; Rodrigo, Pilar; Bonache, Victoria; Hidalgo-Manrique, Paloma; Mohedano, Marta; Rams, Joaquín
An as-cast Mg–1Zn–1Ca alloy has been soundly characterized to be used as a biodegradable material in biomedical applications. Ca and Zn additions have a great influence in the microstructure, mechanical properties and corrosion behaviour of Mg alloys. SEM examinations revealed that most of the Ca and Zn atoms form Mg2Ca and Ca2Mg6Zn3 precipitates, which distribute preferentially along the grain boundaries forming a continuous network of secondary phases. The results of nanoindentation tests show differences in hardness and elastic modulus between the α-Mg matrix and the secondary phases. The results of three-point bending tests shows that cracks propagate following the network formed by the intermetallic compounds at the grain boundaries (GBs). The evolved hydrogen after immersion in Hank’s solution of the alloy has been also estimated, showing a change in the corrosion mechanism after 160 h. The intermetallic compounds act as a barrier against corrosion, so that it progresses through the α-Mg matrix phase.