The characteristics of hydriding and hydrogen embrittlement of a TiAAlAZr alloy were evaluated by the impact test method. The results indicated that the hydrides in TiAAlAZr alloy formed as platelets and were identified as face-centered cubic d-hydride. At room temperature, the specimen showed great sensitivity to embrittlement in ductility by hydrogen. The hydrides formed promoted the crack propagation in the presence of stress, leading to the cleavage failure mode. The impact toughness decreased dramatically with increasing hydrogen concentrations, indicated that the critical hydrogen concentration required to embrittle the alloy might be lower than 300ppm.

The microstructural evolution of a single crystal of yttria-stabilized zirconia (YSZ) implanted with Ti has been studied by cross-sectional transmission electron microscopy (TEM). The implantation of 180 keV Ti ions to a dose of 131017 ions/cm2 was completed at room temperature. After annealing at 1100℃ in an Ar atmosphere for 2h, a phase transition from the fluorite structure of ZrO2 to an isometric pyrochlore structure-type, A2B2O7, occurred due to cation ordering. High-resolution TEM revealed nanodomains of pyrochlore, Y2(TixZr12x)2O7, with a>10.2460.05 Å. The nanodomains of the pyrochlore phase, embedded within the YSZ fluorite substrate, occurred in a depth range from 45 to 105 nm below the surface, which corresponds to Ti concentrations from; 10 to; 15 at. %. The nanoscale pyrochlore precipitates and the YSZ matrix have a completely coherent orientation.

CuZnAl shape memory alloy samples were irradiated by 1.7 MeV electrons under the parent and martensite phase, respectively. The transformation temperatures were measured by differential scanning calorimetry (DSC). The effect of electron irradiation on the ordering degree was studied by X-ray diffraction (XRD) by estimating the spacing difference (△d) of some selected pairs of diffraction planes. The damage accumulation was determined by positron annihilation technology (PAT). The results showed that irradiation under the parent phase produced no change in the transformation temperatures. The reverse martensite transformation temperatures (As and Af) shift to higher temperature of samples and increase with increasing electron doses when irradiation was performed under the martensite phase. The XRD results showed irradiation under the parent phase produces little change in △d, but △d decreased for the CuZnAl samples irradiated under the martensite phase, this implied that the ordering degree of the martensite decreased after the irradiation under the martensite phase. The PAT results showed that the concentration of vacancy clusters increased after irradiation. It is thought that the martensite stabilization is related to the decreasing of ordering degree in the martensite state.

TiNi shape memory alloy samples annealed at 673K for 1h were irradiated within R-phase by 1.7-MeV electrons with different doses. The two-step martensitic transformation temperatures were measured by differential scanning calorimeter. The results indicated that the temperature M of the onset of R-phase-to-martensite transformation decreased with increasing electron dose. The electron irradiation had s a slight effect on the other transformation temperatures. The second lifetime of positrons determined by positron annihilation technology were lowered with increment of the irradiated dose. Relaxation of the elastic stress fields around the Ti Ni precipitates was the cause of 3 4 the observed change of the transformation characteristics because of the migration and accumulation of irradiation-induced point defects.