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A bewildering number of specimen geometries and experimental methods has been proposal (and adopted) to determine the fracture toughness of ceramics.
Images of micro cracks on the surface of the NbC5min sample: a) numerous cracks on the surface of the sample, b) cracks running both through the grain and on the grain boundaries.
Images of micro cracks on the surface of the NbC30min sample: a) numerous cracks on the surface of the sample, b) cracks running both through the grain and on the grain boundaries.
This shows that in the material we have both cracks running through the grain and the grain boundaries.
In the sintered TaC30min material cracks initially go often along the boundaries between grains but then are stopped by multiple scattering on grain boundaries.

There are any different procedures established for the surface treatment of biomaterials, a number of that rely upon the actual application, like orthopaedic surgery.
The grain was refined due to this processes, which the grain size is change into 0.3μm as reported by Konkova, et al (2015).
Meanwhile the Liu, et al (2012) reported that the grain size converted into 47μm.
It clearly shows large grains with without any deformation.
It clearly shows large grains with without any deformation.

Corrosion behavior of cobalt-based Stellite 6 alloy by combustion synthesis and vacuum induction melting XU Yang Tao1,2, XIA Tian Dong1,2,ZHAO Wen Jun1,2,WANG Xiao Jun1,2 1 State Key Laboratory of Gansu Advanced Non-ferrous Metal Materials, Lanzhou University of Technology, Lanzhou 730050, China; 2 Key Laboratory of Non-ferrous Metal Alloys, The Ministry of Education，Lanzhou University of Technology，Lanzhou 730050, China Email:lanzhouxuyt@163.com Keywords: combustion synthesis; cobalt-based Stellite 6 alloy; microstructure; corrosion behavior Abstract: Cobalt-based Stellite 6 alloy rely primarily on carbides, forming in the Co matrix and grain boundaries, for their strength and the distribution, size and shape of carbides depend on processing conditions.
Both the Cr7C3 and CrC carbides were located at grain boundaries and interdendritic regions, forming a continuous network around the columnar grained matrix.
The samples included a large number of carbides such as Cr7C3 and Cr23C6, which were basically chromium carbides containing cobalt in substitution from chromium and MC carbides.
However, the CSed Stellite 6 shown a lot of corrosion pitting and the pits distribute on grain boundaries (b).The corrosion resistance of CSed Stellite 6 was superior to IVMed Stellite 6 because the former solidification rate R was much higher than the later and some non-equilibrium phase could exist at high temperature,which is corresponded well with the results for anodic polarization in Fig.3.
Table 2 Chemical composition (wt.%) of Stellite 6 alloy localized regions by EPMA Stellite 6 alloy Points Mass percent Co Cr Fe W Cl IVMed 1(Grain boundaries) 40.806 35.854 4.078 8.343 10.819 2(Matrix) 55.887 27.828 5.831 7.113 3.341 CSed 1(Pits) 47.226 30.735 2.648 5.296 14.095 2(Matrix) 57.719 28.034 4.584 4.787 4.876 Conclusions (1) Carbides exist γ-Co matrix in the form of Cr7C3, {TTP}12289 Cr23C6 and CrC of CSed Stellite 6, yet the carbides of VIMed Stellite 6 lie single form at grain boundary for Cr7C3 and CrC

The sample surface to form a uniform distribution of the grain size of equiaxed nanocrystals, grain size is concentrated within a range of about a few nanometers to tens of nanometers, the average grain size of about 10nm.
The Octavia and continuous diffraction rings show that there are a large number of crystal grains, and having a large angle between each other and the random orientation difference in the diffraction region.
Pre-pressure rolling technology surfacing repair the surface prepared nanocrystalline layer the surfacing layer surface nanocrystalline layer grain refinement and uniform, small grain size, around about 10nm.
References [1] R.Z.Valiev,A.V.Korznikov and R.R.Mulyukov, Structure and properties of ultrafine-grained materials produced by severe plastic deformation[J], Scripta Metall Mater, 1993,168(2): 141-152 [2] R.Z.Valiev, R.K.Islamgaliev and I.V.Alexanderov.
Microstructure and evolution of mechanically-inducedultrafine grain in surface layer of AL-alloy subjected toUSSP[J].

The impulse current greatly activates the grain surface and reduces the grains activation energy.
SPS sintering takes shorter time and restrains the growth of grains.
At room-temperature fractures, big dimples can be found with both complete grains (from grain decollement) and broken grains.
The reason behind this is that tips of the electrolyzed copper grains were sharp during SPS sintering, leaving a small contact area between grains.
What changed were the number of contact points and the size of contact areas between grains of the electrolyzed copper powder and the rare earth-copper powder.

Since the chemical composition of the alternate layers is identical, there is no contrast due to the electronic scattering, and the only contrast comes due to different number density of 57Fe nuclei.
For example, in a number of studies [12,13] diffusivity of a number of impurities like Au, Cu, Fe, Ti has been measured for a-films of NiZr produced by co-evaporation.
The microstructure of the system consists of nanocrystalline grains of average size 12 nm, embedded in the grain boundary region of the remaining amorphous phase.
This information combined with the fact that the grain boundary region forms a percolating path through the sample, implies that atomic diffusion in n-Fe85Zr15 should occur exclusively through the amorphous grain boundaries.
A collective diffusion mechanism governs diffusion in a-alloys, while in the case of CHM a diffusion mechanism involving rather a small number of atoms was observed.

Sample PSM is composed of two types of grains: elongated crystals (with longer axis about 5-7 µm are embedded into a matrix of polyhedral much smaller grains (about 200 nm).
On the contrary, the mullite grains in specimen BM are equiaxial with average sizes 1.3 µm, and with monomodal grain size distributions.
The microstructure evolution in mullite ceramics is largely dependent upon a number of factors (as in any sintering process), including the properties of precursors, calcination conditions, post-calcinations treatment and the green body forming methods.
The sample with bimodal grain size distributions (PBM sample) exhibited smaller activation energy and greater exponent n (Q=606±33 kJ/mol and n=2.05), than BM sample with equiaxial grains (Q=743±18 kJ/mol and n=1.75).
Elongated crystals are embedded into a matrix of polyhedral much smaller grains.

The corrosion resistance of liquid phase sintered alumina ceramics in aqueous environ- ments strongly depends on composition and chemistry of grain boundary glass formed during sintering.
The first composition labeled as C5 with CaO/SiO2 molar ratio 1:5 is close to that of the glassy phase at grain boundaries in LPS alumina ceramics described in [4,5].
Calcium, silicon and aluminium were leached from the grain boundary glass into the corrosion solution, while the polycrystalline alumina matrix remained relatively intact [4].
In other words, the chemical durability of the material LPS-Al2O3 is indeed defined by the corrosion resistance of the grain boundary glass.
The financial support of this work by the grant of the Slovak Scientific Grant Agency VEGA under the contract number VEGA 1/0206/11 and the grant APVV 0171-09 is gratefully acknowledged.

Introduction This essay is the subject of national eleventh five support schemes: The analysis of key technology on emission reduction and comprehension utilization of solid waste from large iron ore mine (Number:2008BAB32B14).
Nowadays, large-grained iron tailings can be used as sand in construction industry.
The average grain size is 0.19mm.
Obviously，the tailings from this plant fit the ultra-fine sand’s standard well (ultra-fine sand：module 1.5-0.7,average grain size less than 0.25mm).So it will be treated as ultra-fine tailings.
After a number of experiments, both the slag’s specific area can increase to 400m2/kg and the mill’s power consumption is kept in a low level when the grinding time is 55 minutes.

By regulating the pulse waveforms of the applied currents, the chemical composition, grain size, and the individual layer thickness of the electrodeposited Ni-W CMMC can be tailored.
Particularly, by reducing grain size from 47 nm to 3 nm, the specific wear rate coefficient is reduced from 3.79x10-3 µm2/N to 1.11 x10-3 µm2/N [7].
An introduction of W atoms into the Ni matrix results in grain size reduction, due to segregation of W atoms to the grain boundaries of Ni, which in turn thermodynamically stabilize the fine grain structure [1, 3, 27].
Among the different sets of the coatings, the alloys with 29.4 at.% and 6.3 at.% exhibits the smallest and largest grain size, respectively.
The authors point to high hardness that resist deformation under load, and grain relaxation as the controlling mechanisms responsible for the wear resistance improvements.