| 1. |
- Andersons, J., et al.
(author)
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Statistical model of coating fragmentation under equibiaxial load
- 1998
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 13:4, s. 597-602
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Journal article (peer-reviewed)abstract
- A statistical model of coating cracking under equibiaxial tension is proposed based on a Weibull strength distribution for the coating. Crack length and spacing distributions are derived assuming that cracks initiate in random locations and propagate straight till stopping upon encountering a geometiical obstacle (another crack). The theoretical distributions are verified by comparing with simulated cracking patterns obtained by the Monte-Carlo method. An analysis of crack patterns of SiO2 coatings on a PET film under biaxial tension is performed. Qualitative agreement with the theoretical crack spacing distribution is observed.
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| 2. |
- Archana, M. S., et al.
(author)
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Nanocrystalline Phases During Mechanically Activated Processing of an Iron (Fe) Aluminum (40 at% Al) Alloy
- 2014
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In: Materials and Manufacturing Processes. - 1042-6914 .- 1532-2475. ; 29:7, s. 864-869
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Journal article (peer-reviewed)abstract
- Influence of processing conditions on in situ generation of nanocrystalline Fe(3)AlCx and Fe-Al phases during mechanically activated annealing and sintering of Fe-40 at% Al alloy was evaluated. Fe(3)AlCx, Fe3Al and ordered FeAl phases evolved even at a low temperature of 400 degrees C. The presence of carbide phase was attributed to the free carbon originating from the organic process control agent while its formation at low temperature was correlated to fast diffusion of C in the lattice assisted by the nanocrystalline structure coupled with the presence of thermal vacancies in the Fe-40 at% Al alloy. The as-sintered composite showed improved mechanical properties.
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| 3. |
- Hanson, Magnus, et al.
(author)
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Influence from tool roughness on the risk of work material adhesion and transfer
- 2009
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 24:7-8, s. 913-917
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Journal article (peer-reviewed)abstract
- Influence from surface roughness of a forming tool surface on its ability to pick up work material was investigated by laboratory testing. One powder metallurgical tool steel was given different surface roughnesses and tested in sliding contact against one austenitic stainless steel (SS) and one aluminium alloy (Al). Generally, the risk of work material adhesion and transfer increased with the roughness of the tool material. However, SS gave a low friction and very little metal transfer for a tool roughness of the order of the relatively soft SS oxide thickness. The Al alloy, on the other hand, which oxide is much harder than the parent metal, has no critical surface roughness below which adhesive transfer will not occur. The oxide fractures and oxide fragments indent the tool surface increasing the risk of adhesion.
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| 4. |
- Hjarthner-Holdar, Eva, et al.
(author)
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Technology of Iron : Choices and Innovation
- 2009
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 24:9, s. 981-986
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Journal article (peer-reviewed)abstract
- This article deals with the concept of technological change and choices and how new techniques are rejected or accepted in different socioeconomic and power systems. If we are to understand and deal with technological changes, we need to investigate their causes and relations to geographical area and power systems both now and in the past. We have chosen to study the two almost completely different types of societies, Sweden and Greece, in order to understand some of the mechanisms behind the changes in technology and techniques. Our aim is to participate in widening the scope of archaeometallurgy, since traditionally we have focused on empirical analysis of material culture rather than theory building.
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| 5. |
- Jarfors, A. E. W., et al.
(author)
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Mechanism of lubrication-induced surface cracking in hot chamber die cast thin-walled AZ91D parts
- 2003
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In: Materials and Manufacturing Processes. - 1042-6914 .- 1532-2475. ; 18:4, s. 637-641
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Journal article (peer-reviewed)abstract
- Thin-walled hot chamber die cast parts are often used to make telephone casings and similar products having primarily requirements on weight and aesthetically satisfying surfaces. The post casting surface treatment often generates a glossy appearance. The glossy appearance makes it extremely sensitive to small-scale flaws, such as blisters, cold shuts, and cracks. Hot chamber die casting of thin-walled parts requires high filling speed and the use of lubrication because the parts have high aspect ratios. In the manufacturing of such high aspect ratio parts with a wall thickness of 0.6 mm, a new type of cold crack induced by the lubrication is observed. To some extent this defect is similar to a blister, but the characteristic bump is not formed and the actual crack is formed by thermal contraction along the high aspect ratio areas.
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| 6. |
- Jiao, Xinyang, et al.
(author)
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Effect of heating rate on porous TiAl-based intermetallics synthesized by thermal explosion
- 2017
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In: Materials and Manufacturing Processes. - : Taylor & Francis. - 1042-6914 .- 1532-2475. ; 32:5, s. 489-494
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Journal article (peer-reviewed)abstract
- TiAl-based porous materials were synthesized by a novel process of thermal explosion (TE) reaction. The effect of heating rate on expansion behavior of powder assemblies, phase compositions and pore structures were investigated. Results showed that the actual temperature of specimen increased rapidly from 655-661 °C (furnace temperature) to 1018–1136 °C (combustion temperature) in a short time interval of 25–55 s, indicating that an obvious TE reaction occurred at different heating rates (1, 2, 5 and 10°C · min−1). TE reaction in Ti/Al powder assemblies resulted in formation of open-celled TiAl-based intermetallics. When the heating rate was set at 5 °C · min−1, the maximum open porosity of 59% was obtained in Ti-Al bodies, which experienced the highest combustion temperature (1136°C) and underwent maximum volume expansion (48%). The pore size distribution was uniform and pores were interconnected in TE products.
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| 7. |
- Law, Madeleine, et al.
(author)
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Assessment of Mechanisms for Particle Migration in Semi-Solid High Pressure Die Cast Aluminium-Silicon Alloys
- 2020
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In: Journal of manufacturing and materials processing. - Basel, Switzerland : MDPI AG. - 1042-6914 .- 1532-2475 .- 2504-4494. ; 4:51
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Journal article (peer-reviewed)abstract
- In semi-solid metal high pressure die casting and in conventional high pressure die casting, it is common to find a defect band just below the surface of the component. The formation of these bands is not fully understood. However, there are several theories as how they occur, and it has been suggested that segregation is caused by the migration of aluminium-rich externally solidified crystals. In the present work the formation of these bands is investigated theoretically by reviewing suitable potential mechanisms for the migration of such crystals. Two mechanisms are identified as the most probable: Saffman lift force and the Mukai-Lin-Laplace effect. However, it was not possible to identify which of these two mechanisms acted in the case studies. Further testing is required to identify the mechanism that is causing the migration of the aluminium globules and suitable tests are proposed.
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| 8. |
- Li, Donggang, et al.
(author)
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Reactive Diffusion at the Liquid Al/Solid Cu Interface in a High Magnetic Field
- 2011
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 26:6, s. 821-825
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Journal article (peer-reviewed)abstract
- The kinetics of the reactive diffusion at the liquid Al/solid Cu interface was investigated at T = 973 K, 1023 K, and 1073K in a high magnetic field of 11.5 T. During the annealing process, three stable compounds (delta, xi(2), and eta(2)) layers were formed at the interface of the couples, and a power function relationship between the mean thickness of the diffusion layers and the annealing time kept stable. Without magnetic field, the exponent of the power function for each compound layer was higher than 0.5, but it was close to or even smaller than 0.5 with a magnetic field. Compared with the field-free environment, the migration of the liquid/solid interface due to interdiffusion decreased in the presence of a magnetic field. A considerable decrease in the effective diffusion coefficient under a magnetic field provided a likely explanation for the experimental results.
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| 9. |
- Li, Kejian, et al.
(author)
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Effect of ultrasonic shot peening on microstructure and properties of 301SS
- 2017
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 32:16, s. 1851-1855
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Journal article (peer-reviewed)abstract
- Ultrasonic shot peening (USP) is an efficient way to improve the mechanical behavior of 301 stainless steel by inducing severe plastic deformation on its surface. However, this surface treatment induces complex microstructural evolutions, such as grain refinement and phase transformation. Therefore, a better understanding of those evolution mechanisms is critical to optimize the USP treatment. In this work, we rely on various electron microscope observations to compare a specimen before and after a 5-min shot peening treatment. We found an affected layer of ~450 µm with a significant increase in hardness on the top surface by a factor of 2.7 times. Inside this layer, we noticed a nanoscale grain layer of ~130 µm, the most strengthened layer, containing nanoscale grain of α′, with few γ and a large amount of low angle grain boundaries on the topmost. Afterward, we observed coarse grains with deformation twins, which seem to be a preferential site for martensite nucleation, especially at their intersection, and a high density of dislocation. We also conducted experiments to determine a possible scenario for the microstructural evolution, based on those observations.
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| 10. |
- Lloyd-Spets, Anita, et al.
(author)
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New materials for chemical and biosensors
- 2006
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In: Materials and Manufacturing Processes. - : Informa UK Limited. - 1042-6914 .- 1532-2475. ; 21:3, s. 253-256
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Journal article (peer-reviewed)abstract
- Wide band gap materials such as SiC, AlN, GaN, ZnO, and diamond have excellent properties such as high operation temperature when used as field effect devices and a high resonating frequency of the substrate materials used in piezoelectric resonator devices. Integration of FET and resonating sensors on the same chip enables powerful miniaturized devices, which can deliver increased information about a gas mixture or complex liquid. Examples of sensor devices based on different wide band gap materials will be given.
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