Search results

By 1983 most phases likely to be found in fabrication of silicon nitride based materials were characterized as were phase relations in a number of promising additive systems.
Increasing toughness with silicon nitride grain aspect ratio had been reported.
Properties were not yet correlated with microstructure because controlled crystallization and grain growth studies had not been carried out.
We have attempted to present a broad perspective of the field by inviting a number of our colleagues who have made significant contributions over the years to summarize the current status of their fields.
The evolution of this understanding is based on a number of recent experimental observations which are also presented here.

The SEM micrographs of the ceramics sintered at 1450 o C exhibited narrow grain-size distribution with the average grain size around 0.7 µm.
When the powder was calcined at 1000ºC, the Table 1 Microstructure parameters of Ca0.8Sr0.2ZrO3 Samples Lattice-parameter a0 [nm] Crystal phase Space group Mole number in cell CaZrO3 Ca0.8Sr0.2ZrO3 SrZrO3 0.4020 0.4044 0.4094 Cubic Pm3m 1 Fig. 3 SEM micrograph of the Ca0.8Sr0.2ZrO3 grains sintered at different temperatures Fig. 4 Variation of dielectric constant and dielectric loss as a function of frequency solid-state reaction progressed towards the formation of the desired CSZ.
The average grain size of the pellets sintered at 1450ºC is about 0.7µm.

The morphology, grain size and rms values are recorded using Atomic Force Microscopy.
It shows that the spherical shaped grains are distributed without any voids across the sample.
It is clear that the clusters of these grains formed in to bigger spherical grains with an average size of the order of 0.3 μm.
The deposited film at 300 °C is denser and rough because of clusters of grains formed into bigger grains, which is the reason for the roughness of the film.
SEM studies showed the compact spherical grains distributed throughout the films.

This is turn facilitates the flow of water molecules into the interlayer space and an increase in the density of the positive charge on the metal cation, which leads to an increase in the coordination number, i.e. to an increase in the number of hydroxyl groups.
Supercycles with varying numbers of Al and Zn pulses have been used to vary the Al concentration.
The ratio between Al and Zn pulses was increased, while keeping the number of total pulses as close to 500 as possible (e.g. 3% sample: [1 Al- every 32 Zn-pulses] 15 = 495 pulses).
Also, a similar picture can be observed by the preferential orientation factor in the [001] direction, which decreases from 2.81 to 2.79, which is an indicator of a slight change in the structure and grain size changes.
However, the predominant grain growth is observed in the [002] direction, the preferential orientation factor of which is constant and equal.

The current study was carried out to measure the heat resulting from the spontaneous dissociation of some inorganic salts by using sodium chlorate and ammonium perchlorate salts (3gm), iron filings (22gm) with grain size (350 µ), sawdust (7gm) with a size of (200 µ), activated carbon (7gm), and distilled water (8ml), The speed of the reaction was measured and found it was second degree (n=2).
Changing the diameter of the iron filing with the temperature 700 600 500 350 250 diameter of iron filings grains (µ) 28 31 33 55 55 temperatures (C°) 20 30 15 20 10 time (m.)
Changing the diameter of sawdust grains with temperature 250 200 150 100 50 diameter of sawdust particles (µ) 47 55 32 33 29 temperatures (C°) 20 20 25 25 50 time (m.)
Dependence of the temperature on the change in reaction components From the results in tables (1 to 5), the ideal condition obtained in the reaction is the maximum temperature with a gradual or regular increase, the type of iron filings is important in increasing the speed of the reaction and heat generation at range (25-85 °C) and a diameter of the iron filing grains of 350 µ because the transformed of iron to its oxides, Fe2O3 and Fe3O4 needs a medium-sized diameter that not enabling iron filings to enter the grains or deposit inside the gaps which may stop or slow the oxidation-reduction reaction [12]. also, it was found a simple effect of the diameter of the sawdust grains, the best ideal condition (25 - 85 °C) corresponds to a diameter of 200 µ.
Hence, the enthalpy (Hr) depends on the quantity or number of grams of reactants causing heat generation and the total heat capacity (which is the calorimeter constant and the heat capacity of inorganic salts).

When the big inclusions move to the slag , the number of the inclusions decreases at the cost of lower recovery of the alloy.
Samples 1, 3 were used to observe grain size and inclusion precipitation in the steel by CSLM.
Sample 1 in Fig.2(a) without titanium addition has large grain size and few precipitates at the same heat treated conditions.
Grain boundary of sample 3 in Fig.2(d) is distinct and it has good intergranular corrosion resistance compared with sample 1.
Precipitates in the steel increase during heat treated by CSLM and the grain size becomes a little smaller with the increase of titanium added in the steel and grain boundary of the steel becomes more stabile, and intergranular corrosion resistance enhances according to the online analysis results.

It was demonstrated that not only grain size but also such peculiarities of the structure as impurity segregations and/or secondary phase particles in the grain interiors or boundaries effect the mechanical properties of UFG alloys significantly.
The alloy after solid solution treatment (SST) at T = 830 ºС (heating for 20 min) had b-phase grains with a size from 40 to 100 µm.
The optical images of the structure after 1 ECAP pass demonstrate bands of deformation origin inside b-grains elongated along the deformation direction, thickening of boundaries of initial b-grains due to pile-up of dislocations during deformation.
Inhomogeneous etchability of internal areas of the deformation bands in the SEM-patterns of the structure shows that a large number of crystalline defects formed during deformation are accumulated (Fig. 1d) a) b) c) d) Fig.1.
It is seen that in the SPD-processed sample they are smaller than those in the coarse-grained material, and their precipitation took place inside and in boundaries of grains and subgrains, as in this case structure defects (vacancies, stacking faults, subgrain boundaries, etc.) are places where particles generate.

According to the standard and with the actual size of the plate and the number of test samples required for.
So that the grain size improved, low temperature toughness was improved.
Is mainly because the organization and the crystal grain change to cause.
The grain size is improved.
It can be divided into: Coarse grain area has not changed, namely UA CGHAZ (reheat temperature above 1200˚C); Coarse grain over the critical area, namely SCR CGHAZ (reheat temperature between the Ac3 ~ 1200˚C); Critical coarse grain zone, namely IC CGHAZ (reheat temperature between Ac1 ~ Ac3); Coarse-grained sub-critical zone, namely SC CGHAZ (reheat temperature below Ac1).

However, until now only a limited number of studies [7] have been focused on FSW of die casting aluminum alloys.
Because the new grains are shattered by probe before growing up, the grains' size in NZ is very small.
These grains are very trivial, causing microhardness to maintain at a high level.
In HAZ, affected by welding thermal cycle only, the grains are coarse, resulting in the lowest hardness.
Conclusions (1) Trivial equiaxed grains form in the NZ of FSW joints, TMAZ structure has a greater degree of bending deformation and HAZ has slightly grain coarsening phenomenon

Grain coarsening is a major problem in ferritic stainless steels and such grain coarsening causes lower toughness.
To minimize grain growth, weld heat input should be minimized.
Ferrite grain size and carbide precipitation affect the hardness of the FSS.
The HTHAZ exhibited ferritic microstructure with excessive grain coarsening.
Acknowledgements This work is supported by Abant Izzet Baysal University under Contract Number AIBU, BAP. 2016.09.05.1048.