Papers by Keyword: Interface Microstructure

Abstract: The TiN-Al composite coatings on A356 alloy were successfully synthesized by mechanical alloying (MA) of Al, TiN and C powders under argon atmosphere. Meanwhile, the optimal parameters for mechanical milling processing were determined by changing the material ratio (Al: TiN: C), milling time and the ball-to-powder weight ratio, which might have a significant improvement on the wear resistance of A356 alloys. The microstructures and mechanical properties of A356 alloy samples with TiN-Al composite coatings were characterized by means of X-ray diffraction (XRD), scanning electron microscope (SEM) equipped with energy dispersive X-ray spectroscopy (EDS) and Brinell hardness test. It was found that under the optimal conditions, i.e. the material ratio of (Al: TiN: C= 17.5:1.5:1), the ball-to-powder weight ratio of 14:1 and the milling duration of 12 h, the Brinell hardness of sample-6 could be remarkably increased to 143.80 HBW. With the TiN-Al coatings fabricated by MA process, the mechanical properties of aluminum alloys could be significantly improved.

Abstract: The interface microstructure and shear strength weakening of eutectic SnAgCu (SAC)/FeNi-Cu connection after current stressing for 0~12 h were investigated to discuss the stability of the FeNi layer as UBM film layer for Sn base solder. The experiments showed that the FeNi layer separated to two layers with different Fe/Ni ratio rather than intermetallic compound (IMC) thickness variation between the cathode and anode. The IMCs became rougher with a bulk amount of (Cu,Ni)₆Sn₅ emerging in the regains near to interfaces. The shear failure mode exhibited a ductile manner companied by a fracture surface rougher and even grain boundary weakening with the current exposure time increasing.

Abstract: The mechanical properties of PHC pile concrete with different mineral admixture (fly ashground slagground silica sand) were tested and interface microstructure of the concrete were analyzed by ESEM.The result show that,the compressive strength of PHC pile concrete with 20% ground silica sand or with 30% ground slag can reach more than 80MPa after autoclaved curing;The PHC pile concrete with 20% ground silica sand show the best mechanical properties.The tobermorite C₅S₆H₅ can be observed in ESEM photograph of interface of autoclaved curing concrete.

Abstract: The interface microstructure in the joints of magnesium alloy AZ31 to Ti alloy by the laser welding-brazing (LWB) process have been investigated in this paper. The results indicated that the interface between the solder reaction and TC4 formed net and holes, there was a 1~2 μm intermetallic compound layer. Al-Mg-Zn compounds generated and distributed in the solder reaction zone.

Abstract: In this study, the effect of pre-wetting super-light aggregate on the microstructure of the aerated concrete was discussed. The experimental results show that: using Scanning electron microscopy to magnify the interface between mortar and aggregate in aerated concrete to 200 times their normal size, the pro-wet treatment densifies the interface,and to 20000 times,fibrous CSH gel and lamellar tobermorite interweave each other and form very pre-pressing structure on the surfaces .

Abstract: Abstract. The reaction layer microstructure of SiC/SiC joints brazed by Ag-Cu-Ti filler metal, including composition, morphology, grain size were investigated by X-ray diffraction, electronic probe microanalysis, transmission electron microscope. An obvious reaction layer composed of TiC and Ti5Si3 was observed at the interface of SiC substrate and filler metal. There is a representative structure of SiC substrate/continuous fine TiC layer /discontinuous coarse Ti5Si3 layer/filler metal in the reaction layer. The continuous TiC layer, composed of about 10 nm roundish grains, is 350 ~ 400 nm thick. Ti5Si3 layer is composed of only one row of Ti5Si3 grains, which disperse with diverse size from 100 ~ 500 nm. Different growth behavior of TiC and Ti5Si3 is the main reason to form this microstructure.

Abstract: Laser-roll bonding and magnetic pulse welding are two relatively new processes that greatly minimize problems of metallurgical incompatibilities between dissimilar metals and alloys. These two processes, though technologically apart and invented for components with distinct geometries, utilize to various extents high pressures to facilitate rapid and localized interfacial heating and create reliable joints. In this paper, relations between process parameters, microstructures, and properties are discussed for aluminum-to-steel joints made by laser-roll bonding and magnetic pulse welding.

Abstract: Hot-dip galvanized transformation induced plasticity (TRIP) steel sheets were recently developed for automotive applications. The microstructure and the adhesion of zinc coated CMnSi TRIP steel alloyed with P were studied. The α-Zn coating adjacent to the steel substrate consists of a continuous η-Fe2Al5-xZnx inhibition layer with columnar ζ-FeZn13 intermetallic particles on top. Along the interface between the inhibition layer and the steel substrate Mn/Mn-P oxides were frequently observed. Although these oxides at the steel surface reduce the adhesion between the zinc coating and the TRIP steel, they do not cause any bare spots during galvanizing. Upon tensile deformation of the galvanized steel sheet, cracking along the α-zinc grain boundaries preceded fracture of the interface between the α-Zn layer and the inhibition layer. After 4 % deformation the average interface crack length increased linearly with the applied strain. This interface fracture was strongly influenced by the crystalline orientation of the α-Zn grains.

Abstract: The solid microstructure built in the solid governs the properties of materials elaborated from the melt. In order to clarify the dynamical mechanisms controlling solidification processing, we use in situ and real-time synchrotron X-ray radiography at ESRF (European Synchrotron Radiation Facility) to analyze microstructure formation in thin aluminum alloys solidified in the Bridgman facility installed at the ID19 beamline. During directional solidification of Al - 3.5 wt% Ni alloys, global mechanical constraints induced by the shape are found to act on the solid microstructure. In particular, radiography videos of dendritic growth show disorientations of sidebranches induced by mechanical stresses. In the solidification of AlPdMn quasicrystals, live imaging reveals that facetted growth proceeds by the lateral motion of ledges at the solid-melt interface. When the solidification rate is increased, the kinetic undercooling becomes sufficient for grain nucleation and growth in the liquid. These grains develop specific features that can be attributed to grain competition and concomitant poisoning of growth caused by the rejection of aluminum in the melt.