Influence of heat treatment and particle shape on mechanical properties of infiltrated Al<sub>2</sub>O<sub>3</sub>particle reinforced Al-2 wt-%Cu

Miserez, Ali; Stücklin, S.; Rossoll, A.; Marchi, Chris San; Mortensen, Alicja

doi:10.1179/026708302225007754

Cited by 17 publications

(5 citation statements)

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“…Those precipitates are reported to be unaffected by solution heat treatment, [5] which accounts for their continued presence in all the samples (as-cast and solutionized) of the present study; the same observation was made in alumina particulate composites produced using this alloy. [6] Al 7 Cu 2 Fe inclusions tend to decrease the strength of the alloy, as they are brittle and also prevent part of the copper from going into solution during solution heat treatment, thus decreasing the amount of copper available for hardening (2 % copper for 1 % of iron [5] ); this last effect is probably limited given the small amount of iron (0.03 wt. %) present in the alloy.…”

Section: Discussionmentioning

confidence: 99%

Age‐hardening Response of Replicated Microcellular Al‐4.5%Cu

Conde

Mortensen

2008

Adv Eng Mater

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Replication processing of microcellular aluminium begins with the production of a porous preform of internally bonded NaCl powder; this is then infiltrated with aluminium or one of its alloys. [1,2] After metal solidification the NaCl preform is removed by dissolution in water to create a fine interconnected network of metal. One of the key parameters governing the mechanical properties of such a replicated foam is its microstructure, i.e. the inner microstructure of the metal it is made of. The replication process is very flexible in this regard, as it virtually allows the use of any aluminium alloy. Of particular interest in this regard are the classical age-hardening Al-Cu alloys, as these give strengths in the upper range of what is achieved in aluminium alloys.In this study we assess the response of replicated Al-4.5%Cu foams to age hardening, varying the heat-treatment parameters (time and temperature). We investigate in particular the influence of the cell size and morphology, together with that of the foam relative density, on the age hardening of these fine-scale microcellular metals. ExperimentalAl-4.5%Cu open-celled foams having cells 75 or 400 lm in diameter were produced by replication processing. [1,2] In brief, (i) cold-pressed porous NaCl powder preforms were infiltrated with molten Al-4.5%Cu, (ii) the resulting Al-4.5%Cu -NaCl composites were then machined into cylinders with 10 mm diameter and height and finally, (iii) the cylinders were immersed in water to dissolve the NaCl network. The NaCl particles used to produce the preforms are of two types, Fig. 1: (i) 400 lm particles (supplied by Fluka, St. Gallen, Switzerland) produced by NaCl precipitation and of generally equiaxed, cuboidal shape; (ii) 75 lm particles (supplied by Salines de Bex, Switzerland, trade name CP1) produced by grinding, the shape of which is less equiaxed and more irregular. This difference in particle shape is reflected in the mechanical properties of the foams, the more irregular 75 lm particles yielding, at given relative density, foams of somewhat lower Young's modulus than foams produced with equiaxed or spherical NaCl particles. [3] The cylindrical samples were solution heat-treated at 520°C for 4h under argon, and quenched before warm aging in air. Two aging temperatures (130 and 180°C), and seven aging times (2, 6, 10, 20, 54, 168 and 1000 h) were investigated. These samples were tested in compression on an MTS Alliance RT50 screw-driven testing machine, at a displacement rate of 5 lm/s (corresponding to a strain rate of 5 10 -4 ). The load was measured with a 5 kN load cell, and the strain was measured with three LVDTs fixed around the bottom compression plate and measuring the displacement of the upper plate. Table 1 gives the composition of the Al-4.5%Cu alloy used in this study, as measured by the supplier, Alusuisse, Neuhausen, Switzerland (now Rio Tinto Alcan). Figures 2a) and b) show the structure of two replicated Al-4.5%Cu foams: it is apparent that the foam mesostructure, meaning the geometrical metal di...

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Section: Discussionmentioning

confidence: 99%

Age‐hardening Response of Replicated Microcellular Al‐4.5%Cu

Conde

Mortensen

2008

Adv Eng Mater

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“…4 data gathered similarly from a composite of the same F1000 Al 2 O 3 powder infiltrated with Al2wt%Cu at 750°C, (micrographs of this composite are given in [18]). We note in passing that its matrix being softer, it polishes with more difficulty than copper-matrix composites and hence a smaller proportion of the particle/matrix interface was amenable to analysis.…”

Section: Particle Morphologymentioning

confidence: 99%

Al2O3 particle rounding in molten copper and Cu8wt%Al

Krüger

Mortensen

2012

J Mater Sci

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We investigate processing-microstructure relationships in the production of Al 2 O 3 particle reinforced copper composites by solidification processing. We show that during production of the composites by gas-pressure infiltration of packed Al 2 O 3 particle preforms with liquid Cu or with liquid Cu8wt%Al at either 1,150 or 1,300°C, capillarity-driven transport of alumina can cause rounding of the Al 2 O 3 particles. We use quantitative metallography to show that the extent of particle rounding increases markedly with temperature and with the initial aluminum concentration in the melt. An analysis of the thermodynamics and kinetics governing the transport of alumina in contact with molten copper, considering both interfacial and volume diffusion, leads to propose two mechanisms for the rounding effect, namely (i) variations in the equilibrium concentration of oxygen in the melt as affected by the initial aluminum concentration, or (ii) segregation of aluminum to the interface with the ceramic.

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“…Composites produced by infiltrating Al 2 O 3 particle beds with pure aluminium or a binary Al-Cu alloy represent an example of such a model material. These composites feature a high volume fraction (about 50%) of uniformly distributed ceramic particles, which are strongly bonded to a porefree and metallurgically simple matrix (Kouzeli et al, 2001a;Miserez et al, 2002Miserez et al, , 2004b. In both these and other composites in the literature, the nature of damage and its influence on the composite flow stress are now overall relatively well accounted for, even though models are, as mentioned above, of necessity simplified.…”

Section: Nomenclaturementioning

confidence: 97%