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Hardness of a material is dependent on the microstructure of the material like the grain size, packing efficiency, inter molecular bonds and material forming process.
Smaller the grain size harder the material as grains will be more efficiently packed leaving out minimal places for voids.
The benefits of using Taguchi’s method over other methods like full factorial and partial factorial methods is that the former reduces the number of experiments that have to be performed.
Ataie, Role of intensive milling on microstructure and physical properties of Cu80Fe20/10CNT nanocomposite, Journal of Ultrafine Grained and Nanostructured Material, 47, (2014), 37-42

Heterogeneous precipitation at grain interior and grain boundary sites is accounted for, as is the transformation of metastable precipitates to more stable phases.
This model attempts to accurately predict the evolution of the size, number, and distribution of precipitate particles.
The initial size distribution for each phase and precipitation site (grain boundary and grain interior) were determined from TEM studies of parent material (7).

The surface is rough due to etching; the carbide grains are easily distinguishable in the picture.
The carbide grain under the left arrow was found in this AFM image, and was indented.
The other indent is in a carbide grain, the measured hardness is HB = 21.5 GPa which is close to the expected value.
(left: carbide grain, right: matrix) Why is the hardness measured on the right hand side indent much higher than expected?
Acknowledgement This work was supported by the Hungarian Science Foundation under contract numbers T 0300833 and T0034983.

However, a known disadvantage of early PMMA lenses is that they did not allow oxygen to pass through to the cornea, which caused a number of adverse clinical events.
However, an investigation into alternate mould materials with a finer micro grain structure for high performance and high precision polymer lenses presents an alternate method of providing high end optics by injection moulding.
Melt spinning is a revolutionary process which produces ultra-fine and micro-grained aluminium alloys.
Because of its ultra-fine microstructures and absolutely small grain sizes, ultra-high precision diamond machining of RSA 905 can result in extremely low surface roughness of two nanometres or less.
Melt-spun aluminium surfaces are free of the pull-out effect that material grains usually experience in diamond turning unlike traditional optical aluminium (AA-7075 in Table 1).

Polishing was performed in three steps with a final polishing step using a colloidal silica suspension with a grain size of approximately 0.04μm.
The grain size distribution of the different regions of the weld were examined by optical microscopy.
The fine grains indicate that the material is strongly mechanically deformed as a result of the compressive and rotating action of the FSC tool concomitantly pressing out the filler rods.
EDX measurements were performed again within the refined grain region as indicated by the black rectangle in Fig. 8.
Acknowledgements This research was carried out under project number MC8.07290 in the framework of the Research Program of the Materials innovation institute M2i (www.m2i.nl).

Fly ash grains are formed by solidification of the melt, which contains amorphous silica and also a crystalline phase consisting of mullite, quartz and iron minerals.
The resulting fly ash grains are predominantly spherical in shape with a grain size of 0.001 - 0.1 mm and a specific surface area of about 300 m2/kg. [4].
Furthermore, it is necessary to investigate which substances are leached from the kerbs into the substrate by comparative analysis on a larger number of samples.
Závrsky, Testing of possible use of fine-grained alkali activated composites in the construction industry, Materials Science ISSN: 1662-9752, Vol. 865, 47-52

The steel alloys were numbered as 11, 12, and 13 and have the following chemical composition as stated in Table I.
Deformation at a lower temperature than Tr is highly beneficial, where recrystallization if happened it is usually followed by grain growth spontaneously [15].
Coarse grain would lead to creation of upper (coarse) bainite during subsequent treatments [16].
This process would result in pancaked grains [17].
On subsequent treatment, pancaked transformed to fine grained structure, which would create fine bainitic structure later [18] Fig. 8 Flow curves of alloys 11, 12 and 13.

In He8 sedimentary stage, the sandstones generally consisted of medium to coarse grains, with a downtrend of diameter from north to south.
The maximum diameter in the north is 7.0 mm, the average diameter in central-south is 2.4 mm, and coarse grains spread the whole region.
The cumulative grain-size probability curve consists mainly of two-section and three-section, which indicates medium to strong hydrodynamic conditions, which was a good dynamic condition for the development of large- area sand bodies [6].
Sedimentation simulating experiment indicates that with large amount and long duration of water, the number of branches was increased, and mud and sand were carried forward by multiple streams to the lake area.
Strong flow was the major reason for the extensive distribution of coarse grains.

Thus, a large number of studies have focused on the relationship between the mechanical properties and microstructure.
The upper bainite is nodular and has a particular plate-like morphology which can be seen from Fig. 1(c), and the carbides with the shape of short rod simultaneous form along the grain boundary and within the bainitic ferrite.
While the morphologies between quenched bainite and tempered bainite have no significant difference as can be seen from Fig. 2(b) and Fig. 1(c), the quantity and size of carbides do not increase significantly after tempering, and the short rod carbides still precipitate with same orientation in certain region of a crystal grain.

Until now, the investigated alloys are ongoing research to resolve, the investigation was carried out to employ rapid quenching by melt spinning to produce Mn–Ni–In Heusler alloys by JLSánchez Llamazares et al [7], and the ribbons of Ni-Mn-In Heusler alloys grain preferential texture.
According to the Hume-Rothery theory [8], electron concentration is from 7.90 to 8.04 because of the valence electron number of Gd , and the crystal structure stability is decreased so that the martensite transformation temperature rised.
And it is found that the grain boundary second phase increased significantly, due to the increase of Gd content.