A computer simulation of stripe deterioration under electromigration is developed with especial regard to the physical aspects of the process. A grain-boundary network is first established appropriate to a {111} grain-boundary texture by a Voronoi process. Stress relief through the motion of network vertices can be used to simulate the effects of annealing. In operation, two different situations are considered: (1) free-surface condition and (2) operation under a passivating surface containment. With the free-surface condition, voids grow internally while the extra material spreads over the surface. With the passivating condition, the matter is conserved and eventually a steady state ensues. The possibility of sideways extrusions or ‘‘spikes’’ is considered. Many other possible applications of the model are indicated.

Samples of high temperature brazing diamond with Ni-Cr alloy are prepared in protective atmosphere furnace for brazing time is 1 minute, 2 minutes, and 5 minutes. The microstructures were analyzed with Scanning electron microscope, energy dispersive spectroscopy and X-ray diffraction. The results show that there are two layers of carbides on the surface of diamond, lamellar carbide Cr3C2 and columnar carbide Cr7C3, the growth direction of Cr3C2 has a certain orientation relationship with the crystallographic plane of diamond, and Cr7C3 nucleates on the surface of Cr3C2. With the increase of brazing time, the morphology of carbide Cr3C2 turns from linear to lamellar and carbide Cr7C3 turns from granule to columnar. After brazing, chemical metallurgical combination is achieved between diamonds and brazing alloy and carbides are the primary reason for the strong bond strength.

Mono-crystal diamond was brazed with Ni-Cr alloy in protective atmosphere furnace, SEM and XRD were used to analyze the carbides on the surface of diamond and the phases of diamond after brazing, respectively. The results show that the diamond brazed in protective atmosphere furnace can realize high strength connection; the diamond has clear edges and complete morphology after brazing. On the surface of diamond, the arrangement of Cr3C2 is regular, the growth direction of Cr3C2 has a certain orientation relationship with the (111) crystal plane of diamond, all the Cr7C3 nucleates and grows on the surface of Cr3C2, finally, the inner layer is regular arrangement Cr3C2 and the external layer is Cr7C3.

TiC reinforced Fe-based composite coating with 10% and 20% TiC particle were prepared on the surface of substrate Q235 steel by plasma cladding, respectively. The microstructure and formation mechanism of cladding layer were carefully investigated by SEM, EDS and XRD. The results show that metallurgical combination is achieved between coating and substrate, the microstructure of composite coating is composed of dendrite α-Fe, interdendritic eutectic structure (α-Fe, Cr23C6 and CrB) and added TiC particles, and microstructure refinement with the increase of TiC particles content. TiC particles react with Fe-based alloy and part of TiC particles dissolve into coating. The hardness of composite coating has a relationship with TiC particles content and TiC particles distribution, and hardness increase with the increase of TiC particles content. The maximum value of composite coating hardness is 545 HV0.2 and 719 HV0.2, respectively. The major strengthening mechanism is fine-grain strengthening, solid solution strengthening and dispersion strengthening.

Monolayer brazed grinding wheels were prepared using polycrystalline diamond grains, Ni-Cr-B-Si brazing alloy, and commercial Q235A steel with the brazing temperature 1000°C and the holding time 5 min. The microstructure and element distribution of joint interface was studied through scanning electron microscope and energy dispersive X-ray spectroscope, respectively. Grinding performance of wheels was evaluated during grinding alumina specimen. The fracture of polycrystalline diamond grains with the embedding depth of 50 and 70 % was studied quantitatively. The results show that good joint interface was formed among polycrystalline diamond grains, Ni-Cr-B-Si brazing alloy, and Q235A steel through element diffusion and chemical reaction during brazing. Chemical resultants Cr 3 C 2 and Cr 7 C 3 formed within joint interface between polycrystalline diamond grain and Ni-Cr-B-Si brazing alloy; meanwhile, the growth of Cr 3 C 2 has an orientation relationship with element arrangement of diamond surface. Compared with single crystal diamond grinding wheel, the polycrystalline diamond grinding wheel has exhibited evident advantages according to the grinding force and force ration (tangential grinding force F t / normal grinding force F n ). The F n and F t is 21.69 and 7.23 N with the expositing high of 50 % and 5.16 and 1.72 N with the expositing high of 70 % respectively, when polycrystalline diamond grain fracture takes place. The failure mechanism of brazed polycrystalline diamond grains grinding wheel is diamond fracture.