Search results

The number of crystal grains per the cross section of SAC305-6.0In-1.0Sb was stably several tens or more.
In particular, the number of crystal grains of SAC305-6.0In-1.0Sb was 200 or more in all specimens.
Fig. 4 Number of crystal grain in the cross sections shown in Fig. 3.
It means that the clear effect of the number of grains on the range of variance of elongation is not found
(1) The number of crystal grains in Sn-Ag-Cu-In-Sb solder was larger than that of SAC305

Corrosion resistance of ultrafine-grained pure Cu D.R.
The results show that the corrosion rate of the ultrafine-grained Cu decreases, in comparison with the coarse-grained Cu.
The number of ECAP passes is 4.
In contrast, TEM image of the ultrafine-grained sample is shown in Fig. 2 (b).
It is obvious that the anodic current density of the ultrafine-grained Cu decreases and the corrosion potential of the ultrafine-grained Cu becomes more positive, in comparison with the annealed Cu.

But they are strongly dependence on the number of ECAP passes and the pressing route.
Fig. 1 Dependence of the average microhardness on the number of ECAP passes.
Fig. 3 Dependence of static toughness on the number of ECAP passes for 1050 Al.
But they are strongly dependence on the number of ECAP passes and the pressing route
Producing bulk ultrafine-grained materials by severe plastic deformation.

In UFG, slightly elongated grains with an average width of 300 nm were observed, indicating that the microstructure was in the process of evolving equiaxed grains.
Here, a high population of dislocations should still remain in the grain boundary areas as well as in the grain interior.
The mechanical properties before ECAP were 193 MPa tensile strength, 54 % elongation, and a Vickers hardness number of 64.
In addition to this, the whole surface observations of these specimens indicated that the damaged regions were formed at an early stage of cycling, and that the number and area of these regions slowly increased with further cycling up to a specific number of cycles, depending on the material and stress amplitude.
Once this specific number of cycles had been exceeded, both the number and area of the damaged regions showed a significant rise.

This non-uniformity decreases when the number of turns is increased.
With higher number of passes, the grains become more equiaxed.
Figure 6 presents the grain size distribution of ECAE Ta subjected to different number of passes and different routes; note, an increased number of passes leads to decreased average grain size.
Therefore, the effective grain size with a higher number of ECAE passes should be even smaller.
Factors of SPD temperature, routes, number of turns in HPT or number of passes in ECAE, should be considered.

Accumulative roll bonding leads to significant grain refinement.
An ultrafine-grained microstructure with an average grain size of ~ 200 nm [17] is produced after six ARB cycles (Fig. 1 c).
Similarly, burst pressure of the accumulative roll bonded aluminium alloy AA6016 without friction stir welding significantly increases with increasing number of ARB cycles.
Maximum von Mises equivalent strain of AA6016 increases with an increase in number of ARB cycles and reaches a maximum value of approximately 10 % after 6 ARB cycles.
Microstructural investigations showed that the grain size decreases after friction stir welding of the conventionally grained material AA6016, but increases after welding the ultrafine-grained material due to dynamic recrystallisation.

Petal-like icosahedral quasicrystal grains (i-phase grains) morphology usually has been observed in as-solidified quasicrystalline alloys.
In their observation, a very interesting phenomenon that pentagonal dodecahedral Al-Pd-Mn quasicrystal grains connecting each other to form a single i-phase grain has been observed.
(a) 20μm (c) (b) Figs .1(a) single i-phase grain morphology [1] , (b)the attached i-phase grains morphology [2] and (c)petal-like i-phase grains morphology (observed by cross-section) , respectively Now the problem is why the coherent process can take place for i-phase grains?
Consequently, the coherent i-phase grains could be regarded as the connected clusters independently growing largely into the connected i-phase grains.
Some key factors, such as alloy composition and the cooling rate, may directly influence the numbers of i-phase clusters in liquids and the probability of them connecting each other.

But after increasing numbers of turns the hardness increases in the center to the extent that there is a reasonably homogeneous distribution of hardness values across the diameter after a total of 10 turns.
This type of behavior is termed without recovery and it is typical of a large number of metals where the hardness increases with equivalent strain and then essentially saturates [12].
It was observed that agglomerations of the second phase particles may take place at the early stage of processing [19] but an increase in the number of turns promotes homogenization.
Langdon, The strength-grain size relationship in ultrafine-grained metals, Metall.
Zhu, Producing bulk ultrafine-grained materials by severe plastic deformation, JOM 58(4) (2006) 33-39

As the temperature is above recrystallization, some small cracks (or voids) formed along grain boundaries and slip deformation took place in many coarsened grains, while only extrusions and intrusions instead of obvious cracks or voids are observable for UFG Ti.
Experimental Procedures The UFG Ti and Cu rods with an average grain size of ~250 nm were produced by ECAP.
Simultaneously, some small cracks (or voids) initiated along grain boundaries (GBs) and slip deformation took place in many coarsened grains, as indicated in Fig. 1(c).
Analogously, the microstructures of compressed UFG Ti exhibited a somewhat decreased number of GBs than its initial states [10].
Notably abnormal growth of many grains occurred and the maximum grain size has got to more than 2 mm.

The 4 ECA pressed AZ31 alloy revealed the microstructure of dynamically recrystallized grains with a grain size in range of 1 to 10 � .
Journal Title and Volume Number (to be inserted by the publisher) TEM micrographs of AZ31 alloy after ECAP are shown in Fig. 2.
However, the yield stress gradually decreased with increasing the number of pressings unlike the ECA pressed steels and Al alloys reported [2-4].
This was considered to be due to the reduced dislocation density with the number of pressings as shown in Fig. 2 (b).
However, the tensile strength became slightly high with the number of pressings.