Search results

The reduction in grain size can be observed in the microstructure of TSS- samples.
It is revealed that the two-step sintering had an evident effect on grain size reduction, as a grain growth inhibitor.
A fine-grain microstructure can thus be obtained using two-step sintering with average grain sizes ~2.5 μm for sample with 1160/10/1020/6 condition.
This is due to the increase in grain size.
Acknowledgements This research is financially supported by Prince of Songkla University under contract number SCI560371S.

The thermomechanical processing produced non-homogenous microstructures of deformed lamellar grains and recrystallized gamma grains.
Scanning electron microscopy observations used an atomic number contrast mode.
Heat treatments in this domain have the disadvantage of promoting an excessive grain growth.
Optical photomicrograph of microstructure after three step rolling: a) deformed lamellar constituent with a finer grained structure at the grain boundaries; b) detail from (a) showing the duplex nature of the finer grained regions.
However, this treatment induces a coarse grain size.

Second-phase particles not only affect grain growth by pinning grain boundaries and lead to an upper limit of grain size [7], but they also influence the development of microstructure during deformation and primary recrystallization.
Characteristic size parameters of constituent particles, equivalent diameter d and number density were measured by the image analysis software Image-J.
The texture was determined by single grain orientation measurements by EBSD.
In general, pan-cake shaped coarser grains were found for all the three variants, even though the grain sizes are different, as can be seen from Fig.6.
Similar grain structures and grain sizes were obtained for C1-0 and C1-2, while a much smaller grain size was observed for C1-3 due to its less effect from both pre-existing dispersoids and concurrent precipitation.

The sample number 1# 2# 3# The surface hardness 237.3 216.7 192.7 Table 5The surface roughness values of the samples (µm).
Although some grains underwent intense plastic deformation and crack initiation, some grains remained as smooth as the original surface.
As shown in Fig. 5(b), a large number of holes and pits formed on the surface of sample 2#.
In the incubation period, the material suffers a small number of slight CE damage, and the material surface exhibits plastic deformation.
As the CE process proceeds, the plastic deformation becomes intense, and more grain boundaries will be extruded.

MIM is an economic near net shape mass production technique for complex shaped parts, needed in high number.
The number of specimens per set was n=5.
The EDX-mapping pointed out that all alloying elements were mostly distributed onto grain boundaries of the ancient powder particles.
However, solid solution of phases that occur inside of the grains could be disclosed.
These phases could not be found inside of the grains of the as T4- and as T6-material.

SEM showed that the samples uniform in grain size at 1330 °C.
Microsturcture.Fig.2 shows SEM (Ba0.96Ca0.04)(Ti0.95Zr0.05)O3 ceramics surface at different sintering temperature .Figure 4.2 a, b and c shows ceramics grain size has reached nanometer level, and the grain size of graph d and e within a few microns; The microstructure of the samples average grain size tended to increases with the increasing sintering temperature.
As shown in Table 1 is the average grain size of ceramics at different sintering temperature, 1350 °C and 1370 °C sintering ceramic grain size 3.5μm , 4.3μm, respectively, larger than the first three group of ceramic grain size , this is because the temperature is too high, lead to the growth of grain is very difficult to suppress [12].
Other sintering temperature of ceramic crystal defect is more, there are a large number of pores, when sintering temperature is above 1350 °C, the ceramics have burnt, which affect the electrical properties of ceramics.
However, the Curie temperature of the ceramics sintered at 1370 °C is 112°C, this is because the reunion phenomenon in the ceramic grain, grain in the melt.

The structure still consisted of very fine grains of solid solution.
There were almost no change in grains size even after HT at 1000°C for 20 hours (Fig. 8b).
The first grains recrystallization were found out at HT at 1100°C for 20 hours (Fig. 8c).
EDS analysis of ODS initial state Conclusions The mechanical properties, hardness and microstructural of new ODS alloys generation were investigated using a number of different tests.
Until then, the structure is composed from very fine grains of about 100 nm.

Results of densification and grain size.
The presence of well-defined grains and bonds indicates the presence of additives in phase around the grain boundaries.
The results of grain size suggest that the pre-sintering processes avoided the growth of grains.
This smaller grain size contributed to a slightly higher densification.
They made the diffusion process easier, reduced the number of pores and increased the densification, as it was shown on the pre-sintered samples at 830 °C.

Heterogeneous nucleation based on these dispersed particles is enhanced and grain refinement can be achieved [8-12].
Theoretical analysis has confirmed that intensive melt shearing can increase the number density of MgO particles in AZ91 Mg alloy by three orders of magnitude [10].
Jones, Effect of solidification cooling rate on the morphology and number per unit volume of primary Mg2Si particles in a hypereutectic Al-Mg-Si alloy, Metall.
Fan, Mechanisms of grain refinement by intensive shearing of AZ91 alloy melt, Acta Mater. 58 (2010) 6526-6534
[14] TP-1, Standard Test Procedure for Aluminum Alloy Grain Refiners, The Aluminium Association, Washington, DC, 1987

Fringe grain boundary (Saint Paint).
Bold grain boundary (PhotoFiltre).
Some difference of the dimension grain is visible.
At the same time, however, this was accompanied by a much greater number of microcracks.
The thickness of the layer in which the fragmentation of platelets was observed increased with the number of hydrogen-treatment cycles.