Search results

Moreover, because the width and thickness of ingot is large, although the ingot surface has solidified , but there are still a large number of liquid metal in center position, heat is difficult to transfer out, which leads ingot surface remelting phenomenon, it appears cold insulation, hot cracking, warping or ingot tail leakage aluminum defect [1,2,3].
The change of the grain size in the middle of the ingot along the ingot casting radial direction is larger, which in the edge part grain size is uniform due to fast heat dissipation.
a) surface b) heart Fig.4 SEM photos of profile Summary Temperature field and thermal stress field of alloy castings are analyzed by finite element method during solidification process, solidification temperature field and thermal stress field are all not uniform, cooling intensity is also inconsistent, so it is easy to produce a large number of stomata, osteoporosis and other casting defects, At the same time, the surface microstructure of castings was investigated, as far as possible to reduce or eliminate the shrinkage or porosity defects, research results has certain actual engineering significance on aluminum casting ingot solidification process.
Chakraborty: Influence of grain refinement and modification on microstructure and mechanical properties of Al-7Si and Al–7Si–2.5Cu cast alloys.

The HRTEM chart of a small number of samples near carbon edge film is shown in Fig.3.
There is specific disordered amorphous dot contrast between grain and grain.
So the grain is surrounded by amorphous of paclitaxel and albumin.
But the forces are weaker, so it can be imposed through a number of chemical action or mechanical means.

The authors have successfully achieved the grain refinement and associated improvement of fatigue strength due to controlled extrusion [4].
The matrix microstructures consist of equiaxed grain structure with the average grain sizes of 13.1 µm and 12.4 µm for Mg2Si-F and Mg2Si-C, respectively.
Surface crack length, 2c, is represented in Fig.4 as a function of cycle ratio, N/Nf, where N is the number of cycles and Nf the fatigue life.
S-N diagram. 104 105 106 107 108 0 50 100 150 200 Number of cycles to failure Nf Stress amplitude σ (MPa) Mg2Si-dispersed Mg alloy Mg2Si-C Mg2Si-F Extruded AZ31 (b) 200µµµµm (a) 100µµµµm Fig.3.

Fig.1: Different components of laser sintered sample XRD Metallographic structure analysis.Figure 2 is a different Al content of Fe-Al alloy microstructure.The figure shows that combustion synthesis of the samples more uniform microstructure, grain size increases with the content of Al.
This occurs because as the Al content increases, system of heat release increases, the element becomes active diffusion, grain boundary energy increases, more and more coarse grain.
That the rate of diffusion of aluminum to iron is greater than iron to aluminum, resulting in the location of aluminum left a large number of pores, makes synthetic products generate a large number of gaps.And because the process of laser sintering is solid sintering,transient liquid phase sintering and solid sintering, while the transient liquid phase sintering determine the extent of the sample densification.

For this reason a large number of mechanical and electrical products of copper and aluminum parts brazed joints was abandoned, caused a serious waste of resources.Regard this, remanufacturing of Cu-Al brazed composite on the basis of 4R（Reduce, Reuse, Remanufacture, Recycle）is really urgent currently.
In the grains and the grain boundary area, a small number of needle-like compounds are formed.
According to the composition of the brazing filler material, it is believed that the needle-like compounds should be mainly made up of Si grains.

High-magnesium limestone and ordinary limestone were mixed respectively by proportion of 0:1, 1:1, 1:2, 1:3, 1:4, which were numbered as A1, A2, A3, A4 and A5.
The sample was numbered as A0.
The alite mineral grains in A2 are tiny and are enclosed by impurities, suggesting that the clinker of A2 is not sintered completely.
Periclase crystal in these samples is dense, and the shape of alite mineral grains is columnar or hexagonal plate-like, whose size ranging from 30μm to 60μm.
The size of crystal grains is small.

Due to the combination of hardened surface layer with a soft core and the refined prior austenite grain size, IH hardened steels have a good strength - toughness ratio (Koike et al.[14], Hayashi et al.[15]).
Experimental results and discussion Figure 2 is a micrograph of an IH-hardened sample with visible grain boundaries and fine structures formed within the grains.
(a) Number of cycles to failure, Nf, is 2.29×107.
(b) Number of cycles to failure, Nf, is 4.09×107.

Third, In order to better respond to the associate degree of terms, a novel method is proposed which compute the distance in sentence-grain of terms' co-occurrences.
Third, in order to respond to the association degree of terms, a novel method is proposed which compute the distance of terms' co-occurrences in sentence-grain.
(4) Where u is the number of readable cluster labels, l is the number of cluster labels
(5) Where r is the number of documents associated with the labels, n is s the number of documents unassociated with the labels
(6) Where s is the number of all the documents, o is the number of documents with label of ''other''

Duplex ageing refines the grains also.
During the last decade a large number of papers dealing with the decomposition processes in Al-Zn-Mg alloys appeared in the literature [1,2].
Due to the small lattice mismatch of primary Al3Sc particles with the aluminium crystal [7] and the finely dispersed distribution of these phases in the alloy melt [8], the alloy solidifies in an equiaxed fine-grained microstructure.
Sn has been considered as an attractive element for its interaction with a vacancy in the Al matrix and is expected to change the precipitate morphology in the vicinity of grain boundaries.
SEM of fracture surface revealed a good number of dimples indicating a reasonably good ductility for Sn added alloys. 3.

For this reason, a number of research and development studies have examined the process conditions for Sn-Ag-Cu solder alloys and the addition of trace elements.
In contrast to SA solder and SAC solder, the Ni-added solder showed fine β-Sn phases around the joint interface, and a large number of phases were observed.
In the measurements of the thickness of the compounds in this research, grain boundaries were distinguished by identifying the grain boundaries from differences in the etching rate by Ar ion milling, using secondary electron images obtained by FE-SEM, and the thickness of the reaction layer precipitated from the electrode interface was measured.
These values are near the activation energy values for grain boundary diffusion in solder alloy [9].