The effect of microstructure on localized melting at separation in Ti-6Al-4V tensile samples

The phenomenon of localized melting during the separation process of tensile samples has been found in a number of different titanium alloys. In this study, the effect of microstructure on the mechanism responsible for localized melting found on the fracture surfaces of Ti-6Al-4V tensile samples has been investigated. Tensile samples with three different microstructures were strained to fracture at quasi-static applied strain rates, and the resulting fracture surfaces were investigated and characterized using stereo scanning electron microscopy. Selected fracture surfaces were also nickel-plated and sectioned to reveal the subsurface microstructures and to get an idea of the nature of deformation in the region of the fracture surface. Samples which had an equiaxed α microstructure as a result of mill annealing and heat treating showed large regions of concentrated shear and considerable localized melting. By contrast, samples with a finea plate colony microstructure displayed much higher fracture surface tortuosity and no localized melting. The connection between large-scale shear and localized melting implies that a shear instability, such as adiabatic shear, is quite likely a necessary factor for achieving the melting temperature at final separation.     

Reverse ulta-microtomy: a new method of TEM sample preparation

 Two variations of a new method of TEM metal sample preparation are proposed, hereby labeled RUM1 and RUM2, for ”reverse ultra-microtomy” 1 and 2, respectively. With these techniques, the TEM samples are formed from bulk specimens by successively slicing off layers, with an ultra-microtome, until the remnant is partially thinned to electron transparency. This requires the sample to be embedded with excellent adhesion in a mounting material whose mechanical properties resemble that of the sample. While these methods are by far slower than ordinary microtomy wherein the individual slices are used as samples, preparation times are comparable to those for creating TEM samples by standard techniques. Furthermore, the methods (i) can be used where electropolishing fails, (ii) can be favorably applied to finely layered materials and composites, (iii) permit studies of near-surface structure gradients, and (iv) permit the simultaneous observation of an original surface and the underlying material. The methods have been successfully demonstrated through comparisons between samples created through RUM1 and 2 and standard TEM samples. Artifacts caused by the new method of reverse microtoming are shown to be very much reduced compared to direct microtoming. Received: 26 September 1997 / Accepted: 1 October 1997     

Help us creativity researchers, you're our only hope.

I propose suggestions for how creativity can be fostered in the classroom and what creativity researchers can do to facilitate creative growth in students. Suggestions include closing the creativity gap between current education policy and current societal values of creativity, better training of teachers on how to teach creativity, creativity researchers becoming more active and vocal advocates of education policy supporting creativity in the classroom, and changing the language authors use away from a need to enhance creativity and toward the view that creativity needs to be encouraged. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Review of The International Handbook of Creativity.

Reviews the book, The International Handbook of Creativity by James Kaufman and Robert Sternberg (Eds) (see record 2006-05841-000). The International Handbook of Creativity, edited by James Kaufman and Robert Sternberg, provides global perspectives on conceptions of creativity. An edited volume with 35 international contributing authors of 17 chapters, this handbook achieves the goal stated on its back cover of "present[ing] a truly international and diverse set of perspectives on the psychology of human creativity." (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Silicon PV Cell Production on the Moon

A concept has been developed for the production of photovoltaic energy collection systems on the Moon by vacuum deposition directly onto the lunar surface. Using this technique it would be possible to quickly install quite large capacities of power on the Moon at relatively low cost. Most of the material required for photovoltaic devices is readily available on the Moon, and taking production machinery to the Moon can further lower the cost of power if the machinery can be operated for long periods of time. Low-cost energy on the Moon could enable a wide range of activities including support of robust human outposts, production of propellants for use on the Moon or for export, production of a wide range of other materials for use in space, and beaming of energy from the Moon to space and to Earth. A proposed strategy by which lunar power can be developed in the near future is closely connected to the establishment of a human outpost on the Moon.