Dissimilar metal joining between NiTi shape memory alloy（SMA） and stainless steel was conducted.A cluster of NiTi SMA wires were first joined with tungsten inert gas（TIG） welding process,then the NiTi SMA TIG weld...Dissimilar metal joining between NiTi shape memory alloy（SMA） and stainless steel was conducted.A cluster of NiTi SMA wires were first joined with tungsten inert gas（TIG） welding process,then the NiTi SMA TIG weld was welded to a stainless steel pipe with laser spot welding process.The microstructure of the welds was examined with an optical microscope and the elemental distribution in the welds was measured by electron probe microanalysis（EPMA）.The results show that TiC compounds dispersively distribute in the NiTi SMA TIG weld.However,the amount of TiC compounds greatly decreases around the fusion boundary of the laser spot weld between the NiTi SMA and stainless steel.Mutual diffusion between NiTi shape memory alloy and stainless steel happen within a short distance near the fusion boundary,and intermetallic compounds such as Ni3Ti＋（Fe,Ni）Ti appear around the fusion boundary.展开更多
The electron stimulated desorption was used to measure the surface diffusivity of atomic deuterium on clean and boron modified Ni 3(Al, Ti)(110) surfaces. Boron dosing was performed using a solid state boron ion sourc...The electron stimulated desorption was used to measure the surface diffusivity of atomic deuterium on clean and boron modified Ni 3(Al, Ti)(110) surfaces. Boron dosing was performed using a solid state boron ion source. Earlier studies showed that boron dissociates water readily at temperatures as low as 130?K and that the resulting atomic hydrogen is bound to the surface strongly. The surface diffusion coefficient of atomic D on 0.05 monolayer boron modified surface was measured to be about 10 times smaller than that on the clean surface. This slower diffusion of atomic hydrogen may explain why boron improves the ductility of polycrystalline Ni 3Al in moist environments.展开更多
基金Project(50974046/E041607) supported by the National Natural Science Foundation of China
文摘Dissimilar metal joining between NiTi shape memory alloy（SMA） and stainless steel was conducted.A cluster of NiTi SMA wires were first joined with tungsten inert gas（TIG） welding process,then the NiTi SMA TIG weld was welded to a stainless steel pipe with laser spot welding process.The microstructure of the welds was examined with an optical microscope and the elemental distribution in the welds was measured by electron probe microanalysis（EPMA）.The results show that TiC compounds dispersively distribute in the NiTi SMA TIG weld.However,the amount of TiC compounds greatly decreases around the fusion boundary of the laser spot weld between the NiTi SMA and stainless steel.Mutual diffusion between NiTi shape memory alloy and stainless steel happen within a short distance near the fusion boundary,and intermetallic compounds such as Ni3Ti＋（Fe,Ni）Ti appear around the fusion boundary.
文摘The electron stimulated desorption was used to measure the surface diffusivity of atomic deuterium on clean and boron modified Ni 3(Al, Ti)(110) surfaces. Boron dosing was performed using a solid state boron ion source. Earlier studies showed that boron dissociates water readily at temperatures as low as 130?K and that the resulting atomic hydrogen is bound to the surface strongly. The surface diffusion coefficient of atomic D on 0.05 monolayer boron modified surface was measured to be about 10 times smaller than that on the clean surface. This slower diffusion of atomic hydrogen may explain why boron improves the ductility of polycrystalline Ni 3Al in moist environments.
