ZrAlNiCuNb Alloys With The Quasicrystalline And Crystal Precipitates Phase Study By The Transmission Electron Microscopy

Recently, more and more attentions have been drawn to bulk metallic glasses (BMGs) as can be at extremely low the cooling speed (10k/s), and BMGs can be press amorphous form rule of component design, and its itself and has many excellent properties and in precision machinery, aerospace, information technology and weapons industry has great application prospect, due to their unique mechanical and physical properties, for instance, high strength, reformative plasticity and excellent corrosion resistance. The appearance of icosahedral quasicrystal (IQC) as precipitation phase after isothermal annealing is widely reported, indicating the existence of the icosahedral short-range order (ISRO) structure in the amorphous matrix. Quasicrystals have lots of unusual physical properties, for instance, hardness, low thermal conductivity, low friction and remarkable electronic properties. Considerable efforts have been devoted to the investigation of the unique structure and the related defects, which is also the main content of this thesis. The quasicrystalline precipitate exhibits a distinct effect on glass-forming ability, enhanced plasticity and the deformation behavior of the BMGs.So in our paper, we pay more attention on the appearance of icosahedral quasicrystal (IQC) as precipitation phase after isothermal annealing bulk metallic glass (Zr65Al10Ni10Cu15)93Nb7. It is found that most precipitates are icosahedral quasicrystals containing various linear phason strains with The six-dimensional (6D) lattice constant estimated with aq=0.764nm. The corresponding pattern calculated by applying the6D atomic model simplified from IQC Cd-Yb agrees very well with the experimental one and ar=0.540nm. The distortions of the SAED patterns caused by linear phason strains are summarized by theoretical calculation and corresponding experimental examples.In order to clear and detailed analysis of linear phase separation phase seat strain, we established a simple binary simple icosahedron must crystal model, establish coordinate system, The misalignment of the systematic diffraction spots was broadly observed indicating the existence of the phason strain. Based on kinematic theory the diffraction pattern was calculated. The effect of every strain matrix element on diffraction pattern was studied. Then the strain matrix was determined. The distortions of the SAED patterns caused by linear phason strains are summarized by theoretical calculation and corresponding experimental examples. After meticulous measurement, quantitative fitting and calculation of the diffraction spots’ shifting, the phason strain matrices can be determined. The distortions of the SAED patterns caused by linear phason strains are summarized by theoretical calculation and corresponding experimental examples. After meticulous measurement, quantitative fitting and calculation of the diffraction spots’ shifting, the phason strain matrices can be determined. We studied the linear phason strains of quasicrystalline precipititates in (Zr65Al10Ni10Cu15)93Nb7bulk metallic composites by selected area electron diffraction (SAED), and is corresponding the calculation of the phason strain matrices matrices. The spot displacement in the reciprocal lattice indued by linear phason strain as a three dimensional space vector can be divided into three components:one is along the incident beam direction and two is perpendicular to the incident beam direction. In some case,the spot displacement of the (hkl) and(hkl) in the reciprocal lattice induced by linear phason strain can lead to diffraction pattern180°the lack of symmetry. Another two can be according to the displacement vertical or parallel to series of reflection, corresponding for horizontal or vertical. After meticulous measurement, quantitative fitting and calculation of the diffraction spots’ shifting, the phason strain matrices can be determined. The obtained values of the linear phason strains are at10-2magnitude, which suggests that there are preexisting plastic strains in the quasicrystalline precipitates.We also use transmission electron microscopy to learn the methods of characterization (Zr65Al10Ni10Cu15)93Nb7BMG crystal separation phase. A series of SAED are obtained by tilting the specimen along a special kikuchi line of the same area from a TiO2nanoparticle. The tetragonal crystal structure is determined by reconstruction. EDS and EELS spectrum indicate that the nanoparticle mainly contains Ti and O elements. Further HRTEM investigation identifies the (101) twinning in the TiO2nanoparticle. It is necessary to ascertain the origin of the precipitates before studying their influence. The presence of nano-scaled rutile TiO2is probably due to oxidation of the impurity Ti during the melting process, considering the Ti-gettered argon atmosphere.(101)twinning of rutile is common in natural rock and can crystallize during hydrothermal/solid-state high-temperature experiments. The oxygen and the transition metal Ti contamination may stabilize the formation of quasicrystal phase in Zr-base BMG. And the scale of Zr3Al2identification of crystalline phase are presented.