The high mechanical strength and corrosion resistant nature of oxide dispersion strengthened (ODS) superalloys puts them in demand for use in extreme applications such as turbine engines and heat exchangers. Much of their suitability for these applications is derived from their carefully tailored microstructures. Unfortunately some joining methods, like welding, can alter the desirable microstructures and therefore the properties of the superalloy.
Transient Liquid Phase (TLP) diffusion bonding has emerged as a potential joining technique for advanced alloys when fusion welding and other solid state processes are not suitable. The process involves using an interlayer between the surfaces to be bonded. The interlayer contains materials that lower the melting point. At the bonding temperature, which is below the melting temperature of the parent alloy, the interlayer melts and a joint forms by isothermal solidification.
In the present work, R.K. Saka and T.I. Khan of the University of Calgary, used Transient Liquid Phase diffusion bonding to join Inconel MA 758 using nickel based interlayers.
The researchers investigated the effect of interlayer composition, bonding time and the use of post-bond heat treatment on microstructural developments at the joint region. They found that the hold time at the bonding temperature affected the rate of isothermal solidification during the TLP bonding process. They also found that altering the hold time could produce a joint free from deleterious centerline eutectic structures. The formation of intermetallic precipitates adjacent to the joint interface were observed for bonds made using all four interlayers and a proper selection of interlayer composition was shown to reduce precipitation. The use of post-bond heat treatment was also found to help homogenization of the joint microstructure.
For graphite pellets, just add elbow grease
23.03.2018 | Rice University
23.03.2018 | Fraunhofer-Institut für Produktionstechnik und Automatisierung IPA
Satellites in near-Earth orbit are at risk due to the steady increase in space debris. But their mission in the areas of telecommunications, navigation or weather forecasts is essential for society. Fraunhofer FHR therefore develops radar-based systems which allow the detection, tracking and cataloging of even the smallest particles of debris. Satellite operators who have access to our data are in a better position to plan evasive maneuvers and prevent destructive collisions. From April, 25-29 2018, Fraunhofer FHR and its partners will exhibit the complementary radar systems TIRA and GESTRA as well as the latest radar techniques for space observation across three stands at the ILA Berlin.
The "traffic situation" in space is very tense: the Earth is currently being orbited not only by countless satellites but also by a large volume of space...
An international team of researchers has discovered a new anti-cancer protein. The protein, called LHPP, prevents the uncontrolled proliferation of cancer cells in the liver. The researchers led by Prof. Michael N. Hall from the Biozentrum, University of Basel, report in “Nature” that LHPP can also serve as a biomarker for the diagnosis and prognosis of liver cancer.
The incidence of liver cancer, also known as hepatocellular carcinoma, is steadily increasing. In the last twenty years, the number of cases has almost doubled...
In just a few weeks from now, the Chinese space station Tiangong-1 will re-enter the Earth's atmosphere where it will to a large extent burn up. It is possible that some debris will reach the Earth's surface. Tiangong-1 is orbiting the Earth uncontrolled at a speed of approx. 29,000 km/h.Currently the prognosis relating to the time of impact currently lies within a window of several days. The scientists at Fraunhofer FHR have already been monitoring Tiangong-1 for a number of weeks with their TIRA system, one of the most powerful space observation radars in the world, with a view to supporting the German Space Situational Awareness Center and the ESA with their re-entry forecasts.
Following the loss of radio contact with Tiangong-1 in 2016 and due to the low orbital height, it is now inevitable that the Chinese space station will...
Fraunhofer Institute for Organic Electronics, Electron Beam and Plasma Technology FEP, provider of research and development services for OLED lighting solutions, announces the founding of the “OLED Licht Forum” and presents latest OLED design and lighting solutions during light+building, from March 18th – 23rd, 2018 in Frankfurt a.M./Germany, at booth no. F91 in Hall 4.0.
They are united in their passion for OLED (organic light emitting diodes) lighting with all of its unique facets and application possibilities. Thus experts in...
A new scenario seeking to explain how Mars' putative oceans came and went over the last 4 billion years implies that the oceans formed several hundred million...
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23.03.2018 | Materials Sciences
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23.03.2018 | Physics and Astronomy