The creep behaviour of aluminium-alumina (SAP) alloys

Bonnet, P.; Kellerer, H.; Piatti, G.; Schleicher, H.W.

doi:10.1016/0036-9748(68)90245-7

Cited by 5 publications

(2 citation statements)

References 4 publications

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“…In previous work [1][2][3] the influence of temperature on strain-induced cavitation in AI-AI~Oa (SAP) alloys was studied after tensile and creep tests. At high temperature a high rate of crackformation was found.…”

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Density measurements after tensile and creep tests on pure and slightly oxidised aluminium

Beghi¹,

Geel²,

Piatti³

1970

J Mater Sci

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In order to investigate the influence of dispersed oxide particles on crack-formation in AI-AI2Oa alloys, series of tensile tests (20 to 550 ~ C) and creep tests (450 ~ C) were carried out on pure AI and on AI-0.7 wt~ AI203 specimens. Density measurements performed on broken samples showed no changes in pure AI but considerable decreases in the slightly oxidised AI. The observed influence of oxide is strong for the small percentage if compared with the behaviour of AI-AI203 alloys with much higher oxide contents.In previous work [1-3] the influence of temperature on strain-induced cavitation in AI-AI~Oa (SAP) alloys was studied after tensile and creep tests. At high temperature a high rate of crackformation was found. It was observed [1] that the extent of cavitation as measured by a density change, increased slightly with increasing alumina content (from 4 to 14 wt ~ AlcOa), following an irregular trend at different temperatures. In the present work comparative experiments were carried out on pure aluminium and slightly oxidised aluminium.The materials used were obtained from high purity aluminium ingots (A1 99.99%) extruded into bars of 20 mm diameter (temperature 500 ~ C, extrusion ratio _~ 12). Some of these bars were utilised for the pure A1 samples: average measured density 2.6984 g cm -a. For the preparation of the oxidised material the remaining bars were swaged to a diameter of 2 ram, and oxyacetylene sprayed in air to obtain a slightly oxidised powder. This powder (dimension of particles < 200Fro) was subsequently hotpressed and extruded (temperature 500 ~ C, extrusion ratio _ 12) into bars of 20 mm diameter. Average measured density for this oxidised material: 2.6946 g cm -a.Chemical analysis showed the sprayed material to have an oxide content of 0.70 wt ~. The theoretical density of this material cannot be stated because of uncertainty of the density of the alumina. The oxide was present in the form (A L C O A denomination) as determined by 9 1970 Chapman and Hall Ltd.X-ray diffraction on the alumina extracted from the matrix; the method is described in [4]. The alumina powder, after extraction, was also examined by electron microscopy; the morphology was similar to that of aluminium oxide extracted by the same method from SAP alloys.The tensile and creep specimens for both the oxidised and pure aluminium material had a gauge length of 50 mm with diameter 10 ram. For both materials two series of experiments were carried out: (a) Tensile tests at different temperatures from 20 to 600~ cross-head speed of 3 mm rain -1 (strain rate 1.0 • 10 -~ sec-1). (b) Accelerated creep tests with constant load at 450 ~ C at different levels. Density measurements were carried out by the immersion technique according to the method described in [2]. Microscopical examination was carried out on several specimens in order to follow eventual grain growth during the experiments.In fig. 1 the ultimate tensile strength and the total elongation are plotted against the temperature. The results for the total elongation are rath...

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Density measurements after tensile and creep tests on pure and slightly oxidised aluminium

Beghi¹,

Geel²,

Piatti³

1970

J Mater Sci

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“…The porosity in our electroformed alloys was studied through density measurements since such studies are commonly used to measure residual porosity in sintered materials and are also applicable to studying porosity in dispersion-hardened alloys (6). The density of Au-A1203 samples weighing 1.5g each were determined with an immersion technique using an analytical balance with a sensitivity of 0.1 mg.…”

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