Advanced Materials Research Vols. 146-147

Abstract: Fly ash has become increasingly wide range of applications in expressway as a new environment friendlymaterial, its range of applications are fromthe CFG( Cement Fly-ash Gravel) pile of soft ground、pavement admixture to embankment materials et al. Fly ash used in expressway has many advantages, such as, it can save farmland, has a small settlement after construction and low cost as a light embankment filling. In this paper, based on an expressway in Jiangsu province, the fly ash used as a subgrade filling, a series of fly ash laboratory and field test have been conducted. The construction technology, important construction parameters, construction process control and compaction quality assessment on fly ash have been analyzed on the basis of the tests result, the road performance and construction control key methods of fly ash obtained, which can guide scientific construction.

Abstract: Considering with the spatial characteristics of concentrated deformation field caused by the micro-cracks concentration and localization in rock, a new damage variable is defined based on the standard deviation of the strain fields of rock specimen surface during loading. When digital speckle correlation method (DSCM) is used to measure the deformation fields of rock specimen, the damage variable definition in this paper takes great advantages on damage measurement of rock methods. Using the new methods, the damage of rock would be measured for the whole loading process and the experiment is easy to be implemented. The validity of the proposed damage variable is verified by the experimental results on column-shaped marble specimen subject to uniaxial compression.

Abstract: Two tricarbonyl rhenium complexes with the formula of [Re(CO)3(L)Cl], where L=1,10-phenanthroline (Phen-Re) and 2-(3-thienyl)-imidazo[4,5-f]-1,10-phenanthroline (TIPh-Re), were successfully synthesized and characterized by 1H NMR and UV–Vis with the aim to analyze the effect of the thiophene(TI) moiety on the photophysical properties of TIPh-Re. It was found that the introduction of an π-electron density moiety into diimine ligands leads to a dramatic red shift of the absorption of the corresponding Re(I) complex. At the same time, the results verify that the triplet metal-to-ligand charge-transfer dπ(Re)→π*(N-N) emission (3MLCT) of Phen-Re and TIPh-Re centered at ca. 566 nm and ca.569 nm, respectively.

Abstract: The tribological properties of AZ71E and AZ91D magnesium alloys were comparatively investigated at ambient and elevated temperature. The results indicated that the wear rates of both alloys increased with increasing load, whereas the friction coefficients decreased with increasing load. The wear resistance of AZ71E alloy was significantly superior to that of AZ91D at higher loads and elevated temperature. At ambient temperature, abrasive wear is the predominant wear mechanism for AZ71E, whereas the wear mechanism for AZ91D transfers from abrasive wear to delaminative wear. At elevated temperature, the predominant wear mechanism of both alloys changed from mild wear regime to severe wear regime.

Abstract: Texture evolution in the MDF processed ZK60 along forging axis was investigated by advanced neutron diffraction. Texture analysis was related to the deformation mechanism. Results showed that basal planes deformation was dominated and accommodated by non-basal and twinning. Gradient texture indicated an inhomogeneous distribution of imposed strains along forging direction. This could be related to the non-precise MDF processing.

Abstract: Drawbead is an important factor to automobile sump forming process, proper drawbead setting can improve the forming quality significantly, such as uniforming the sump thickness. Using the drawbead setting theory in dynaform software, the drawbead on the compressive annular part which lie in the shallow part of sump was set, that is, three separate line segment shape equivalent drawbead were arranged alone the shallow part of the die. The influence law of different drawbead parameters to the sump thickness variation has been simulated. Simulating results show that after setting drawbead, reduction of sump thickness is reduced 15% relative to not setting one, and drawbead setting has significant influence to the sump forming quality. It is helpful for forming mold design.

Abstract: AlTiC master alloys have been prepared by Contact Reaction Method（CRM）.X-ray diffraction，SEM and EDS were used to analyses the AlTiC master alloys. It showed that morphology and distribution of TiC and Al3Ti particle have correspondingly changed with the change of the size of powder. As a result, the change in morphology and distribution of TiC and Al3Ti particle has considerably affected the gain refining performance of AlTiC master alloys. The result showed that: when the grain size of Ti is much smaller, the effect of refinement is much better.

Abstract: Worldwide materials science diffractometers at large scale facilities were built recently to improve experimental options for the characterization of advanced materials. Thermal neutrons as well as hard X-rays have a relatively high penetration power that non-destructive investigations of stress profiles and texture gradients are possible. Due to the main difference between neutrons and photons, which is the brilliance of the beam, the gage volume of synchrotron experiments is much smaller than with neutrons. That means, according to the material itself local resolution in mm-scale is preferred by neutrons and in μm scale by synchrotron radiation. The microstructure of laser welded Al shows fine grained parts were synchrotron radiation can be used while coarse grained parts need neutrons for better grain statistics. Both radiations can also be used to perform in situ experiments for stress and texture analysis. A combination of neutron and synchrotron measurements was used to explain the texture influence on the activation of twinning during Mg-extrusion. Neutron diffractometers, such as Stress-Spec@FRM II/Garching-Germany, or synchrotron diffractometers, such as Harwi-II@Haslab/Hamburg-Germany, are excellent for materials characterization in combination with electron diffraction and laboratory X-ray diffraction.

Abstract: Pseudo solder is one kind of familiar solder joint defect, and it is very difficult to be detected in surface mounted technology. Reduce the pseudo solder is viewed as one of effectively way to keep the quality of solder joints. In this manuscript, the quality of component, solder paste printing process, mounting processing, reflowing process, solder material are analyzed to illustrate the cause of pseudo solder in surface mounted technology. Based on the five factors, a pseudo solder model is built for IC component. In the pseudo solder model, its parameters are used corresponding to the cause of pseudo solder, and their values are used to evaluate the degree of satisfaction based on the SMT technological process. Experiments results show that parameters of the pseudo solder model can illustrate the cause of pseudo solder effectively.

Abstract: Two kinds of welding methods were performed on 22APU stainless steel: laser welding and TIG welding. In this case, the differences of the corrosion characteristics of the welded zones between the two welding methods mentioned above were investigated with electrochemical methods such as the measurement of corrosion potential, polarization curves, cyclic voltammogram, etc. The Vickers hardness of all welded zones (WM:Weld Metal, HAZ:Heat-Affected Zone, BM:Base Metal) was relatively higher for the laser welding than for the TIG welding. Furthermore, the laser welding method’s corrosion current densities in all welding zones were also observed to have a lower value compared to TIG welding. In particular, the corrosion current density of BM, regardless of the welding method, was the lowest value among all other welding zones. Intergranular corrosion was not observed at the corroded surface of all laser-welded welding zones; however, it was observed at the TIG-welded WM and HAZ welding zones, which suggests that chromium depletion due to the formation of chromium carbide occurs on the WM and HAZ which are in the range of sensitization temperatures, therefore the zones can easily be corroded with a more active anode. Consequently, we can see that corrosion resistance of all welding zones of 22APU stainless steel may be improved by the use of laser welding. Keywords: Laser welding, TIG welding, Corrosion potential, Weld metal, Heat affected zone, Polarization curves, Chromium depletion1.Introduction In recent years, use of austenitic stainless steel, which has a high corrosion resistance, has been increasing due to the development of industries, such as atomic energy, aerospace, petro chemical, etc. When stainless steel was welded for numerous kinds of structures, intergranular corrosion would often be observed at the area surrounding the welding zone due to chromium depletion; in addition, there are numerous papers which have investigated both general corrosion and intergranular corrosion[1-6]. However, there are few experimental results on the effect of corrosion control at the welding zones when laser or TIG welding are used for the purpose of constructing heat exchangers with 22 APU stainless steel. Although laser welding is more expensive than TIG welding, laser welding is often used instead of TIG welding for the production of heat exchangers. Consequently, it has been suggested that, from a long-term point of view, laser welding is more economic than TIG welding. In this study, when TIG and laser welding are performed on the stainless steel, the differences of the corrosion characteristics in the welding zone was investigated with electrochemical methods. The experimental results are therefore expected to provide useful reference data for the appreciation of mechanical and corrosion characteristics in the welding zones.