The electron-stimulated desorption was used to measure the surface diffusivity of atomic deuterium on clean and boron-modified Ni₃(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 130K 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 Ni₃Al in moist environments.

The effect of coating repair on microstructure and mechanical properties of a directionally solidified nickel base alloy IC6 was studied. The experimental results show that after coating repair treatment, the substrate/coating interface keeps well, and the combination of coating and substrate is very good , as well as very slight mutual diffusion of alloying elements between substrate and coating occurred. Although coating repair treatment make diffusion time double, only a little amount of Mo diffused into coating, and the elements Cr and Co of NiCoCrAlYHf coating only exist in a thin layer of influence region of the substrate, which has no obvious effect on the microstructure of alloy IC6. Tensile tests at room temperature and stress rupture tests under 1100℃, 90MPa of the coating-repaired sample were conducted. The results show that the coating repair has no evident effect on mechanical properties. Therefore, it may be considered that when the coating is unexpectedly destroyed, it can be repaired.

The effect of aging at 950℃ for up to 2000h on microstructure and mechanical properties of alloy IC6A was investigated with scanning electron microscopy(SEM), transmission electron microscopy(TEM) and energy dispersive spectroscopy(EDS) of electron probe micro-analyzer(EPMA). The results show that Ni₃Y and Mo_1.24Ni_0.76 precipitated in the interdendritic area due to the addition of yttrium have no obvious change during high temperature aging. A needle like or rod like phase named Y-NiMo precipitated after aging for about 200h. The a mount and size of the Y-NiMo phases increase with the increase of aging time, which is similar with that in alloy IC6. The ultimate tensile strength at room temperature and stress rupture life under 1100℃, 90MPa of alloy IC6A have no obvious change before aging for 1000h and decrease obviously with increasing aging time after aging for 1000h. The yield strength of alloy IC6A at room temperature decreases obviously after aging for 500h and however, has no obvious change during further aging.