Crack formation in sintered two-phase alloys

Kellerer, H.; Piatti, G.

doi:10.1007/bf00549731

Cited by 6 publications

(4 citation statements)

References 4 publications

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“…Equilibrium of attractive and repulsive forces in the metallic lattice and equilibrium distance of atoms or lattice parameter r 0 , respectively. [1] Fig. 2.…”

Section: Zero-dimension Defects Thermal Activation Of Atomsmentioning

confidence: 99%

“…[32] For titanium, it is known that the passivation layer is dissolved in the bulk at elevated temperatures and hence is no obstacle for a good joining quality by diffusion welding. [1] For aluminum and its alloys, however, the presence of a very stable passivation layer is a severe problem.…”

Section: Surface Conditionsmentioning

confidence: 99%

“…Due to the specific requirements of the process, the complexity, and since extensive experiments for process optimization are necessary for different materials, contrary to conventional welding techniques, its application remained limited to cases without other alternatives, such as for example joining of thin titanium sheets for reinforcing applications in the aerospace industries. [1] During the diffusion process, normally no liquid phase is formed. By adjusting appropriate conditions for temperature, time, and surface pressure, the mechanical properties across the joined part are comparable to the bulk material.…”

Section: Introductionmentioning

confidence: 99%

“…Over the last decades, several authors have addressed diffusion welding of different materials for various applications rather broadly. [1][2][3][4][5] However, it must be noted that often not all the necessary information about the materials used, the procedures for sample preparation or the process parameters applied for diffusion welding are given, and hence the results are difficult to reproduce.…”

Section: Introductionmentioning

confidence: 99%

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Considerations of Microstructural Influences for Diffusion Welding of Metals in Microsystem Technology

et al. 2013

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Diffusion welding is a special high‐tech solid joining technique. Most research was done and publications were written in the years between 1970 and 1980. The aim of this paper is to take a closer look at the fundamental processes inside the material during diffusion welding and to discuss the relation between the materials microstructure for diffusion processes from a material science point of view. For this, it is necessary to discuss the impact of different lattice defects and to observe the intrinsic energetically conditions of a metal originating from its delivery state and manufacturing history, as well as its surface condition. In particular, emphasis is paid to the special requirements for joining of micro process devices.

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“…Equilibrium of attractive and repulsive forces in the metallic lattice and equilibrium distance of atoms or lattice parameter r 0 , respectively. [1] Fig. 2.…”

Section: Zero-dimension Defects Thermal Activation Of Atomsmentioning

confidence: 99%

Section: Surface Conditionsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Considerations of Microstructural Influences for Diffusion Welding of Metals in Microsystem Technology

et al. 2013

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Void formation at the interface between particles and matrix in deformed Al-Al2O3 foils

Ruedl

1969

J Mater Sci

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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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Crack formation in sintered two-phase alloys

Cited by 6 publications

References 4 publications

Considerations of Microstructural Influences for Diffusion Welding of Metals in Microsystem Technology

Considerations of Microstructural Influences for Diffusion Welding of Metals in Microsystem Technology

Void formation at the interface between particles and matrix in deformed Al-Al2O3 foils

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

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