Abstract: We investigated the crystallization behavior of the melt-spun Cu50Zr45Ti5 alloy ribbon on
thermal annealing and electron irradiation using a transmission electron microscopy (TEM). The
structure composed of a monoclinic CuZr phase with an average grain size of about 8 nm and a glassy
matrix was formed by electron irradiation induced crystallization, while by thermal annealing the
equilibrium Cu10Zr7 and CuZr2 crystalline phases directly precipitated in the glassy phase of the
Cu50Zr45Ti5 glassy alloy.
Abstract: Rod-shaped precipitates in Al -1.1 mass% Mg2Ge (balanced) and Al -1.0 mass% Mg2Ge –
0.5 mass% Mg (excess Mg) alloys aged at 523 K were observed by high-resolution transmission
electron microscope (HRTEM) to understand their crystal lattices and chemical compositions.
Rod-shaped precipitates were parallel to <100> directions of the matrix. There were 2 groups for
rod-shaped precipitates in the base alloy, namely, small cross sections about 10 nm and large ones
over 20nm in diameter. Small precipitates showed a hexagonal network of bright dots in their
HRTEM images, and its crystal lattice was estimated as a hexagonal having a= 0.72 and c= 0.405 nm
based on analysis of HRTEM images and selected area electron diffraction (SAED) patterns. This
lattice parameter was slight larger than that of the β’-phase in Al-Mg-Si alloy.
Abstract: Intragranular bainite is known to be effective to develop toughness greatly in steels.
Effects of aging below eutectoid temperature before austenitization, the deformation before solution
treatment and the duration of solution treatment on nucleation of intragranular bainite have been
examined. In the austenite (γ) region where carbide pre-existed, the stress due to inverse
transformation, ferrite (α) to γ, would be introduced into fine austenitized region with lower transus
temperature to γ, resulting in the introduction of stable small-angle boundary at high temperatures
acting as the nucleation site for intragranular bainite lath. Deformation of α by cold rolling before
solution treatment enhances the nucleation of intragranular bainite, suggesting that the above γ
region through the inverse transformation is easily deformed by the hardened neighboring α. In the
deformed γ region, small-angle boundary would be more easily introduced, acting as nucleation site
for intragranular bainite. Intragranular bainite lath grew and hardness decreased by prolonging the
duration of solution treatment, indicating that transformation stress introduced by the pre-treatment
was influenced by solution treatment. The effect of sulfur addition on formation of intragranular
bainite was also analyzed.
Abstract: Relaxor ferroelectric Pb(Mg1/3Nb2/3)O3 (PMN) crystals were grown at low temperature by
a single-step hydrothermal process, using the mixture of PbO, MgO and Nb2O5 as precursors. The
precursors were just heated to 150 oC for 24 h. The effect of the KOH concentration on the
morphology and microstructure of PMN crystals was systematically investigated. The optimum KOH
concentration was found to be 11M, which led to the stabilization of the perovskite crystals against
the pyrochlore phase, and to the growth of high-quality PMN crystals suitable for subsequent
characterization. According to morphological evolution during the reaction, two possible growth
mechanisms are proposed. When the KOH concentration is 11M, at the early stage of the reaction, the
starting materials dissolve, and then promote the formation of spherical intermediate pyrochlore
phase followed by the formation of primary cubic PMN crystals. At the same time, a platelet-shaped
intermediate pyrochlore phase also forms and then grows into larger platelet-shaped PMN crystals.
Abstract: Microstructure evolutions and hardness variation during aging in metastable β titanium
alloy TIMETAL®LCB have been examined. In as-quenched specimen after solution treatment,
athermal ω phase formed. Isothermal ω phase formed during aging at 623 K, and α phase formed after
precipitation of isothermal ω phase during aging at 673 and 773 K. Alpha phase nucleated at
isothermal ω phase, and had the orientation relationship with β and ω, (111)β//(0001)ω//(1120 )α and
[10 1 ]β//[1120 ]ω//α . During aging at 873 K, α phase formed without isothermal ω phase.
Hardness increased with increasing aging time and decreasing aging temperature, partly because
number density of isothermal ω or α precipitates increased with increasing aging time and decreasing
Abstract: The charging effects on non-conductive materials due to electrons irradiation were
investigated by electron holography. The phenomena that the charging effects were more enhanced
with an increase in the incident electron density were visualized through the direct observations in
the electric potential distribution around the specimens. In addition, through the comparison
between the electron holography results and the simulations, we were able to obtain the quantitative
results indicating the amount of charges accumulated during electron irradiation.
Abstract: Superconductivity in two Li-containing compounds of Li2Pd3B and Li2Pt3B was recently
discovered. These materials, showing the superconducting transition at 7.2 K and 2.6 K,
respectively, have the same cubic structure (P4332) composed of distorted octahedrons without
mirror or inversion symmetry along any directions. This is a very interesting feature of those
materials in relation to the symmetry of superconductivity. Resistivity measurements in magnetic
fields gave their upper critical fields, Hc2(0) = 45 kOe and 19 kOe, respectively. Their specific heat
was measured using a heat-pulse relaxation method. The Sommerfeld coefficient (γ) and Debye
temperature (θD) terms of Li2Pd3B were given as γ=9.5 mJmol-1K-2 and θD=228 K . The value of
C/γT at Tc was calculated to be 1.7. In the same manner, those parameters were described for
Li2Pt3B as γ=9.6 mJmol-1K-2, θD=240 K, and C/γTc =0.75, respectively. Since C/γTC in the weakcoupling
limit by the BCS theory is 1.43, the value of 1.7 for Li2Pd3B is slightly higher. The
electronic specific heat of Li2Pd3B at a zero magnetic field follows the typical exponetial behavior
discribed in the BCS theory, while that of Li2Pt3B shows quadratic behavior. This result suggests
the line nodes exist in the superconducting gap of Li2Pt3B driven by the spin-orbit interaction.
Abstract: The contribution of nano-scale particles observed using Atom Probe Tomography in an
increase of yield strength of conventional and advanced HSLA steels was studied. The advanced
HSLA steel showed higher yield strength than conventional HSLA steel. There were two types of
carbides, which primarily contribute to an increase in yield strength of conventional HSLA steel: (i)
coarse TiC with average size of 25±5nm and (ii) fine TiC with average radius of 3±1.2nm. The
presence of two types of carbides was found in the microstructure of advanced HSLA steel: (i)
nano-scale Ti0.98Mo0.02C0.6 carbides with average radius of 2.2±0.5nm, and (ii) C19Cr7Mo24 particles
with an average radius of 1.5±0.3nm. The contribution of precipitation hardening in the yield
strength of advanced HSLA steel due to the nano-scale particles was 174MPa, while this value in
the conventional HSLA steel was 128MPa.