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Shock compression experiments were performed on amorphous Ce3Al melt-spun ribbons using the 50 J laser shock loading system at the Omega laser facility. A multi-layered sample of 2mm total thickness with 1 mm × 1.5 mm width and 40 µm thick ribbons sandwiched with 6 µm epoxy was used as the target in order to study the effects of varying pressures (due to attenuation) on the transformation behavior. The shock-induced changes were characterized post-mortem via synchrotron XRD analysis. Comparisons of the initial amorphous, thermally devitrified (at 500°C), and shock compressed samples indicate devitrification under high pressure shock compression into the thermodynamically stable hexagonal α-Ce3Al intermetallic phase, similar to the thermally devitrified samples.

Thin film metallic glasses (TFMGs) exhibit properties superior to their bulk counterparts allowing them to be potentially useful in many practical applications. Apart from their technological interest, when converted to crystallized state (devitrification) TFMGs can also act as precursors for partially crystallized or fully crystallized forms. Such devitrified forms are attractive due to their novel structural and magnetic properties. The amorphous-to-crystalline transformation of co-sputtered Ni-Zr alloy thin films through annealing was studied using EXAFS (Extended X-ray Absorption Fine Structure) measurements. Investigation through an atomic probe gives a better insight into the local environment of the atomic species, rendering a deeper understanding of thermal evolution of such materials.

A comprehensive study of optical and mechanical properties of quartz glass (fused silica) with regard to application in high temperature solar receivers is presented. The dependence of rupture strength on different surface conditions as well as high temperature is analyzed, focussing particularly on damage by devitrification and sandblasting. The influence of typical types of contamination in combination with thermal cycling on the optical properties of fused silica is determined. Cleaning methods are compared regarding effectiveness on contamination-induced degradation for samples with and without antireflective coating. The FEM-aided design of different types of receiver windows and their support structure is presented. A large-scale production process has been developed for producing fused silica dome shaped windows (pressurized window) up to a diameter of 816 mm. Prototypes were successfully pressure-tested in a test bench and certified according to the European Pressure Vessel Directive.

The glasses in the system MnNbOF5-BaF2-InF3 have been firstly synthesized and studied. The thermal parameters of these glasses are analyzed. It was stated that glass of the composition 40MnNbOF5-40BaF2-20InF3 is the most thermal stable in the system under study. By X-ray analysis the compositions of the crystalline phases obtained at the glass thermal treatment were determined: the main phases are Ba3In2F12 and BaNbOF5. By Raman and IR spectra analysis it was stated that the networks of glasses in the system are built by the structural type of the glasses in NbO2F-BaF2 system: (NbOnFm) polyhedra joined oxygen bridges. Indium trifluoride forms InF6 polyhedra, which are embeded between oxyfluoroniobate ions, forming a common networks or forms its own layers from InF6 polyhedra. IR-spectroscopy method showed that at devitrification of the sample 30MnNbOF5-50BaF2-20InF3 the band position and shape change in going from glass state to crystalline. The bands in the range 900–700 cm−1 shift into the low-frequency...

Selenium based chalcogenide glasses are attractive candidates for IR devices due to their low transmission loss. Thermal studies for Ge19Se81-xSbx (x = 0, 4, 8, 12, 16, 17.2, 20) have been carried out using differential thermal analysis. Glass transition temperature has been calculated using Tanaka's relation. Marseglia's and Ozawa's methods have been used for the calculation of activation energy for crystallization. Effect of Sb addition on GeSe base system shows that resistance to devitrification increases up to x = 17.2.

Phase coexistence of competing magnetic phases, down to the lowest temperature, gained prominence in half-doped CMR manganites where theoretical models suggested that the ground state is not homogeneous. Following experimental studies invoking novel paths in [H,T] space, researchers at Indore pushed an alternative view that this phase coexistence could be due to the kinetic arrest of the underlying first order magnetic transition. The formation of a magnetic glass consisting of one equilibrium ordered magnetic phase and a metastable phase of competing magnetic order, has now been found to be ubiquitous due to the kinetic arrest of many first order magnetic transitions. The CHUF (cooling and heating in unequal field) protocol created at Indore allows the observation of 'devitrification', followed by 'melting' [1-5]. In this talk I shall show examples of CHUF measurements establishing kinetic arrest in various materials, emphasizing our recent studies on magnetic shape memory alloys. I shall address, with e...

Magnetic field and temperature dependent magnetization measurements have been carried out for undoped and Ca doped GdBaCo2O5.53 samples using CHUF (Cooling and Heating in Unequal Fields) protocol. The measurements reveal that the kinetically arrested metastable glass like phase persists in the pristine sample and the volume fraction of magnetically arrested phase increases by substituting Ca. Glass like devitrification or de-arrest of frozen phase with increase in temperature is evident in both the samples.

Crystallization of gas‐atomized Al‐4.3Y‐3.8Ni alloy powder during consolidation has been studied ex‐situ in a transmission electron microscope using high‐resolution lattice imaging together with the image simulations, selected‐area diffraction and energy‐dispersive X‐ray spectrometry experiments. The as‐atomized powder is predominantly amorphous but some particles others show evidence of decomposition. On the application of heat and pressure two types of decomposition product are formed initially; equiaxed nanoscale α‐Al grains embedded in an amorphous matrix, and dendritic aluminum grains containing complex ordered structures. The ordered structures in the α‐Al were identified as Guinier‐Preston like zones: thin sheets of solute rich material parallel to {100} and {110} aluminum planes with ordered cubic symmetry. Amorphous and micro‐crystalline phases are in between the aluminum‐rich regions. The second and third stages of crystallization involve the conversion of these ordered phases and embryonic precipitates to the better‐known binary and ternary compounds.

Devitrification of Co‐based amorphous alloys, enhanced initial permeability and giant magneto‐impedance have been studied for the samples of composition, Co68Fe4Ni1Si15B12, Co67Fe4Ni2Si15B12 and Co67Fe4Mo2Si15B12. Ultra‐soft magnetic properties has been observed by appropriate annealing manifested by high initial permeability of the order of 104 and low relative loss factor of 10−6. Giant magneto‐impedance ratio (GMIR) has been obtained for these compositions measured with a current driving frequency of 4.5 MHz. Field dependence of GMIR response varies for different composition and annealing condition.

The mechanism of glass devitrification to form Bi2Sr2CaCu2O8 (Bi‐2212) superconducting powders is determined using high‐temperature X‐ray powder diffraction (HTXRD), thermal analysis, and quench studies. This technique is shown to be a rapid and straightforward method for producing fully crystalline, phase‐pure Bi‐2212 powder. The peritectic melting sequence of devitrified Bi‐2212 glass powder is mapped using HTXRD, and the melt‐texturing process is also investigated. The effect of melting temperature and cooling rates on final phase content and crystal alignment are determined. A process for producing high‐purity, well‐oriented Bi‐2212 thick films is presented.