Abstract: Non-toxic allergy free alloying elements are mostly selected for preparing metallic
biomaterials. Currently, functionalities such as low modulus, shape memory, super elasticity, etc. are
required for the metallic biomaterials, especially for β type titanium alloys. The harmonization of
metallic, ceramic, and polymer biomaterials is needed for advanced biomaterials in the future.
Titanium and its alloys are attracting considerable attention with regard to applications not only in the
biomedical field, but also for dental and healthcare products. In dentistry, titanium and its alloys are
applied to dental products such as crowns, inlays, bridges, etc., as well as dental implants. For
fabricating dental products, the dental precision casting process is important. A new dental precision
casting process using calcia is currently being developed. Noble alloys such as gold base or silver
base alloys are widely applied for the precision casting of dental products. Allergy-free elements,
particularly Pd-free low- noble dental alloys are required.
Abstract: The Representative Volume Element (so-called RVE) is the corner stone of continuum mechanics.
In this paper we examine the scaling to RVE in linear elasticity, finite elasticity, elasto-plasticity,
thermoelasticity, and permeability of random composite materials.
Abstract: Friction stir welding (FSW) has been in use for nearly fifteen years and a significant
body of published research regarding process/property/structure relationships is now available;
particularly with respect to FSW of aluminum alloys. In this paper, some pertinent literature will be
reviewed and an attempt made to tie the numerous experimental observations together through some
unifying concepts. Examination of relationships among control and response FSW process
variables (respectively e.g. tool rotation rate and torque) and weld microstructure and properties can
provide important insight regarding how weld properties develop and how best to approach process
development for different alloy classes.
Abstract: The body-centered tetragonal (BCT) structure in quenched Fe-C steels is usually
illustrated to show a linear change in the c and a axes with an increase in carbon content from 0
to 1.4%C. The work of Campbell and Fink, however, shows that this continuous linear
relationship is not correct. Rather, it was shown that the body-centered-cubic (BCC) structure is
the stable structure from 0 to 0.6 wt%C with the c/a ratio equal to unity. An abrupt change in
the c/a ratio to 1.02 occurs at 0.6 wt%C. The BCT structure forms, and the c/a ratio increases
with further increase in carbon content. An identical observation is noted in quenched Fe-N
steels. This discontinuity is explained by a change in the transformation process. It is proposed
that a two-step transformation process occurs in the low carbon region, with the FCC first
transforming to HCP and then from HCP to BCC. In the high carbon region, the FCC structure
transforms to the BCT structure. The results are explained with the Engel-Brewer theory of
valence and crystal structure of the elements. An understanding of the strength of quenched
iron-carbon steels plays a key role in the proposed explanation of the c/a anomaly based on
interstitial solutes and precipitates.
Abstract: The quality of steel sheets is strongly affected by the surface defects that can be generated
during hot rolling and are often related to scales removal operation. These defects are related to
rather complex high temperature oxidation processes. In order to reduce an occurrence of the
defects, it is necessary to understand better the formation of iron oxides during high temperature
oxidation, the structure of the interfaces with the substrate and between different oxide phases.
However, due to the lack of good experimental research tools details of iron oxide microstructures
were not investigated. Conventional methods, such as backscattered electron images or fractography
can only provide general characteristics of microstructures like grain morphology and grain size.
In this paper the microstructure, phase distribution and texture in oxide formed during high
temperature oxidation of iron and low carbon steels are investigated. The oxide microstructures are
characterized by orientation imaging microscopy (OIM) on the cross-sectional area of the oxide
layers. It is demonstrated that OIM using electron backscattered diffraction (EBSD) techniques, can
be used to distinguish grains having different phase composition and orientation and can become
invaluable tool for visualizing the oxide microstructure, texture and also can be used to study oxide
defects. The three different iron oxides phases can be distinguished and the characteristics of oxides
with different oxidation histories compared The characteristics of high temperature oxidation
microstructure of iron are presented with description of iron oxide defects and cracking as well as
the illustration of the interfacial microstructure between the layered iron oxides.
Abstract: Yield strength of highly dislocated metals is known to be directly proportional to the
square root of dislocation density (ρ), so called Bailey-Hirsch relationship. In general, the
microstructure of heavily cold worked iron is characterized by cellar tangled dislocations. On the
other hand, the dislocation substructure of martensite is characterized by randomly distributed
dislocations although it has almost same or higher dislocation density in comparison with heavily
cold worked iron. In this paper, yielding behavior of ultra low carbon martensite (Fe-18%Ni alloy)
was discussed in connection with microstructural change during cold working. Originally, the
elastic proportional limit and 0.2% proof stress is low in as-quenched martensite in spite of its high
dislocation density. Small amount of cold rolling results in the decrease of dislocation density from
6.8x1015/m-2 to 3.4x1015/m-2 but both the elastic proportional limit and 0.2% proof stress are
markedly increased by contraries. 0.2% proof stress of cold-rolled martensite could be plotted on
the extended line of the Bailey-Hirsch equation obtained in cold-rolled iron. It was also confirmed
that small amount of cold rolling causes a clear microstructural change from randomly distributed
dislocations to cellar tangled dislocations. Martensite contains two types of dislocations;
statistically stored dislocation (SS-dislocation) and geometrically necessary dislocation
(GN-dislocation). In the early deformation stage, SS-dislocations easily disappear through the
dislocation interaction and movement to grain boundaries or surface. This process produces a
plastic strain and lowers the elastic proportional limit and 0.2% proof stress in the ultra low carbon
Abstract: Numerous methods have recently emerged for fabricating cellular lattice structures with
unit cells that can be repeated to create 3D space filling systems with very high interconnected pore
fractions. These lattice structures possess exceptional mechanical strength resulting in highly
efficient load supporting systems when configured as the cores of sandwich panels. These same
structures also provide interesting possibilities for cross flow heat exchange. In this scenario, heat is
transported from a locally heated facesheet through the lattice structure by conduction and is
dissipated by a cross flow that propagates through the low flow resistant pore passages. The
combination of efficient thermal conduction along the lattice trusses and low flow resistance through
the pore channels results in highly efficient cross flow heat exchange. Recent research is investigating
the use of hollow truss structures that enable their simultaneous use as heat pipes which significantly
increases the efficiency of heat transport through the lattice and their mechanical strength. The
relationships between heat transfer, frictional flow losses and topology of the lattice structure are
discussed and opportunities for future developments identified.
Abstract: Significant technical challenges still remain today for the fuel cell in a number of areas
including reliability, durability, cost, operational flexibility, technology simplification and
integration, fundamental understanding and life cycle impact. New advanced materials and
associated innovative engineering design will be required to close these technical gaps. This paper
provides a perspective on fuel cell technology today, research and development directions,
challenges going forward, and a future view of the fuel cell.