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The main disadvantage of doping with manganese (even in a small amount) is a significant increase in grain when heated [6].
In Research [10] the fatigue strength at bending of technical aluminum and Al-1.0% Mg alloy mainly depends on the grain size and the type of semi-finished products.
Cracks are predominantly formed at grain boundaries inclined at 40-60° to the extension direction, which indicates that the shear stress affects the formation of a crack.
This indicates that hardening, associated with grain boundaries, causes the formation of cracks.
On the other hand, the density of precipitates at grain boundaries does not affect the appearance or propagation of a crack.

However, multilayer ZTZ had much larger grain size compared to the single layer and bilayer.
It is depends on grain size, orientation and grain boundaries.
A grain boundary is identifying as the interface at which grains move towards and contact with another different crystal orientation.
Several kinds of defect are present at grain boundaries such as dangling and impurities [23].
VOL 11, Number 9, 8143-8147 (2011)

Fig.2j shows a typical Widmanstätten structure with α grain boundary in the prior β grains from 1050 furnace cooling.
The grain size tends to be coarse.
The number indicates the heat treatment temperature.
The enlarged microstructure (Fig.3 (a)) shows the α´ martensite structure and β phase between martensitic laths inside of the grains in FZ.
From 950A to 1050A, α grain boundary in the prior β grain starts to appear.

Micro-alloying elements such as Nb, Ti, and V serve to refine the grain size and introduce precipitation strengthening.
Martensite transformation was observed at austenite grain sizes of 15 and 30 μm.
Moving from the surface towards the center, the amount of pearlite increased, accompanied by an enlargement in grain size.
The grain size at the surface and 1/4 position ranged around Classes 9-10, while the grain size at the center approached Class 7.5.
Measurement of G-phase volume fraction and number density in duplex stainless steels using transmission electron microscopy, Materials Today Communications, 38 (2024), 107, 926.

Compared to the above-mentioned types of fibers, basalt fiber has a number of advantages, namely: higher tensile strength and a wide temperature operation range.
At the stage of preparation, crushing of the rock is carried out, the size of the grains of the crushed rock should not exceed 50 mm.
The essence of the centrifuged concretes’ variatropic structure lies in the uneven distribution of aggregate grains over the product thickness.
The largest aggregate grains are located at the outer surface of the product, and those that are smaller are located closer to the inner surface.
This uneven distribution of aggregate grains over the product thickness is the main distinguishing feature of centrifuged concrete in comparison with vibrated concrete [9-11].

FESEM and HRTEM images showed that the samples were highly crystalline, and the grain size increased as the temperature increased.
Fig. 6 shows the XRD patterns of ZnO nanoparticles with their plane number.
The average grain sizes of the samples that were annealed at 200°C and 300°C were 31.32 nm and 51 nm, respectively.
The grain size increased as the temperature increased from 200°C to 300°C [21-22].
FESEM and HRTEM images show that the samples had high crystallinity, and the grain size increased as the temperature increased.

· No phase change, no oxidation and no grain growth due to a lack of heating of the powders
Bae et al. [119] observed two regions in titanium deposit: a region of larger grains (>250nm) with high dislocation density and a region of smaller nanocrystalline grains (<100nm) with dislocation free grain boundaries.
Also, the fine grained nano structure can promote grain boundary sliding and consequently enhance ductility.
Zahiri et al. [115] reported that annealing at 350-550 °C resulted in ultrafine grains (<5 µm) formation in 25% of the area with an average grain size of 7µm.
The ultrafine grains provide the mechanical strength to the deposits and larger grains provide the ductility to the material.

This is because the removal process in the grinding is in fact concerned with the individual interaction between diamond abrasive grits and individual tungsten carbide grains.
Fig. 1: Microstructure of cemented tungsten carbide (WC) that consists of WC grains (grey phase) and cobalt binders (black phase).
As shown in Fig. 1, the cemented tungsten carbide consists of tungsten carbide grains and cobalt binders.
The tungsten carbide grains have shapes of nearly triangle, rectangular and trapezoidal, with sizes ranged from 200 nm to 1 mm.
Summary Based on the grinding protocol described above, a number of micro/meso aspheric moulds made of cemented tungsten carbide were fabricated using only three grinding cycles.

Vacancies are annihilated and generated at appropriate sinks and sources such as dislocation jogs, incoherent interfaces, grain boundaries and free surfaces.
The second is the annihilation of excess vacancies at grain boundaries (GB) with radius R.
The grain size of the dilute Al alloy is taken to be 1 mm, the dislocation density is set to 1011 m-2.
We assume that the density and efficiency of sinks (grain boundaries and dislocations) remains constant and do not change during the quench.
The mean grain diameter is set to 100 µm and the dislocation density is 1011 m-2, identical to the settings in the pure Al system.

In recent times, a number of methods have been developed to create nanostructures of CeO2 that are considerably various from the techniques used for producing bulk materials, such as ball milling [5], hydrothermal [6], sol-gel [7], and so on.
Furthermore, it was found that the dimensions of the grain size increasing and tend to agglomeration as the calcination temperature an increases [20].
It was also observed that the direct band gap reduces with an increase in the grain size of the CeO2 NPs.
The reduction in band gap due to the increase of grain size of CeO2 NPs may be attributed to the occurrence of oxygen vacancy as defects [1].
By calcining CeO2 between 500 and 800°C, the grain size of the sample was increased and tended to amalgamate.