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At the same time, the matrix grain boundaries were weakened by Cl element.
The fracture surface were intergranular features and covered with a large number of corrosion products, cracking and secondary cracks, which were the main characteristics of stress corrosion cracking, as shown in Fig.7.
After peak aging of 7B04 aluminum alloy, the GP region of semi lattice precipitates in the grains of 7B04 alloy, and continuous dispersed phase is distributed on the grain boundary.
This kind of grain boundary structure is very sensitive to stress corrosion, especially in the presence of Cl-.
Meanwhile, the fracture surface was analyzed by EDS after ultrasonic cleaning, and the Cl element was relatively high on the fracture surface, which indicated that Cl element weakened the grain boundaries of matrix and existed on the grain boundaries.

The carbide precipitation on the grain boundaries was also studied.
Points/regions of interest are identified with numbers.
After the thermal exposition, all samples were analysed by SEM/EDS and the chromium, nickel and molybdenum contents were determined inside the grain and near the grain boundary (Table 1).
Table 1 - Chemical analyses performed inside and near the grain boundaries by SEM/EDS.
Chromium [%] Nickel [%] Molybdenum [%] GRAIN BOUNDARY 17,05 10,73 1,03 SPECIMEN NB. 1 INSIDE THE GRAIN 16,55 11,77 0,82 GRAIN BOUNDARY 17,11 11,15 1,46 SPECIMEN NB. 2 INSIDE THE GRAIN 16,26 11,99 0,85 GRAIN BOUNDARY 16,55 11,9 0,94 SPECIMEN NB. 4 INSIDE THE GRAIN 17,2 11,42 1,98 GRAIN BOUNDARY 15,81 12,52 0,81 SPECIMEN NB.5 INSIDE THE GRAIN 16,44 11,16 0,98 GRAIN BOUNDARY 16,67 10,89 0,57 SPECIMEN NB. 6 INSIDE THE GRAIN 17,09 11,61 1,57 GRAIN BOUNDARY 16,82 11,43 0,94 SPECIMEN NB. 7 INSIDE THE GRAIN 16,67 11,78 0,92 Conclusions From the observation of the fracture surfaces taken out from the structure, it is intelligible that a transgranular fatigue crack propagation occurred, eliminating the stress corrosion and the creep crack propagation hypotheses, which should reveal a intergranular crack propagation.

This corresponds to increase of grain size and increase of [h00] texture.
We have quantitatively compared size of such grains with the results of XRD data.
The grain size vs.
With the increase of grain size, the number of grain boundaries decreases and a decrease of the total resistance would be expected.
Resistance of the thin film is increasing with the grain size.

(5) Test methods: a) Number of tests: It is generally stipulated that two tests should be carried out at each inspection (so-called double samples).
The quality of sintered ore with grain size of 0.00-5.00mm and 10.00-16.00mm is obviously increased, while the quality of other grain-grade sintered ore is reduced by two groups.
The other laws of the grain size distribution are consistent with the above.
Moreover, when the number of drums is the same, the degree of pulverization of the sinter is greater as the drum time increases; when the drum time is the same, the pulverization degree of the sinter is partial with the increase of the number of drums low; when the number of drums and the drum time are the same, the degree of pulverization of the sinter is basically the same, and the test results satisfy the error tolerance range.
The following conclusions are drawn: (1) When the number of drums is the same, the degree of pulverization of the sinter is greater as the drum time increases; (2) When the drum time is the same, the degree of chalking of the sinter is lower as the number of drums increases; (3) When the number of drums and the drum time are the same, the degree of pulverization of the sinter is basically the same, and the test results satisfy the error tolerance range.

The final effect of twinning on strain hardening rate depends on the number of factors introduced by the twinning itself in the process of sliding.
The analysis of the twinning geometry in particular grains showed that twinning is primarily developed for systems with the highest Schmid factor.
However, despite the large number of studies on this steel, many features related to microstructure, phase composition, work hardening and damage remain unclear.
However, the final effect of twinning on strain hardening rate depends on the number of factors introduced by the twinning itself in the process of sliding [10].
In these cases, the driving force for the twinning could be associated with the internal stress field due to the inconsistency of the deformation of neighboring grains.

Moreover, TiC0.5N0.5 has the effect of crystal nucleus, which makes a fine grain size of Si3N4.
At the same time, grain size is large and the pull-out effect of columnar crystal of silicon nitride is little.
At the same time, grain size is smaller and the pull-out effect of columnar crystal of silicon nitride is high.
However, the increase in the concentration of TiC0.5N0.5 caused a increment in the number and the size of micro-cracks.
Long columnar particle shape class whiskers formed, on account of anisotropy of grain growth of β- Si3N4.

The multiphase eutectic products distributed both inside grains with agglomerate aspects and along the α-Al interdentritic regions or at grain boundaries, which is contained with Si and Al2Cu.
In order to control the grain size and increase the strength, both Mn and Cu were added.
These two irregular strip and blocky black and grayish products are all distributed along the grain boundary or interdendritic.
The other elliptical or dish one with distinct eutectic pattern lies in grain constituted AlMgCuSi with or without Fe, while the content of Si is very high (excess atom fraction 20%).
Whereas the number of such slice-like ultrafine dispersoids increases evidently after HT at 743K within 5h (as shown in Fig. 7).

For A357 alloys, fscoh values increase after grain refined and melt superheat treatment.
On remelting for grain refinement and modification testing, the alloys were grain refined with 0.1 wt pct Ti in the form of an Al-5wt pct Ti master alloy and were modified with 0.01wt pct Sr in the form of an Al-10wt pct Sr master alloy.
The nucleation process determines the number of dendrites and the distance between them, i.e. the growth distance of dendrite coherency.
Lack of extensive branching gives a slower increase in solid fraction in the melt grain refined.
For A357 alloys, fscoh values increase after grain refined and melt superheat treatment. 3.

Introduction According to statistics, every autumn, there are great quantities of leaves in the cities, and the number is increasing.
It can be seen from Table 3 that the factors affecting 5min diffusivity are in order of DCAEB, i.e., W/B＞varieties of superplasticizer＞varieties of cement＞leaves grain size＞leaves species.
The optimum choice is D3C1A3E1B4, i.e., the best W/B is 0.7, superplasticizer is SL-A, cement is P.S32.5, leaves grain size is 0.3mm, and the best type of leaves is magnolia.The factors affecting 35min diffusivity are in order of DCBAE, i.e., W/B＞varieties of superplasticizer＞type of leaves＞varieties of cement＞leaf grain size.
The best water-reducing agent is SL-A, the ideal cement is P.S32.5, and best leaves should be magnolia leaves with 0.3mm in grain size.
The best superplasticizers is SL-A, the ideal cement is P.S32.5, and best leaves should be magnolia leaves with 0.3mm in grain size.

The grinding tool is Resin Bond Diamond Wheel, and the number of its grain size is 240#.
Q is the sum of squared of residues. n is the number of tests. p is the number of variables.
When other condition is certain, the number of active grains would increase with the increasing of linear speed of grinding wheel.
So, if the linear speed is lower the number of active grain is few in unit time.
The SEM photos on vs=34.54m/s with magnifying 80000 times Conversely, if the linear speed of grinding wheel is high, the number of active grains would increase in time.