The liquidus surfaces and the isothermal section at 973 K of the pseudo-ternary BaO-ZnO-B2O3 system were determined using the thermal analysis and X-ray diffraction. The liquidus surface in equilibrium with ZnO spreads over a wide composition range and that in equilibrium with 5ZnO•2B2O3 extends long and narrow toward BaO•B2O3. The slope of the liquidus surface in equilibrium with ZnO is steep in the region of less than 20 mol%B2O3 but gentle when the B2O3 content exceeds 20 mol%. The liquidus surface in equilibrium with 3BaO•B2O3 widely extends and its slope is gentle in the region of less than 30 mol%B2O3 but steep when the B2O3 content exceeds 30 mol%. Pseudo-ternary BaO-ZnO-B2O3 compounds were not found in the composition range investigated. The ternary eutectic reactions are as follows: L→3BaO•B2O3+BaO•B2O3+ZnO, occurring at 1033 K at the composition 46.5 mol%BaO-14.5 mol%ZnO-39.0 mol%B2O3, L→BaO•B2O3+ZnO•B2O3+5ZnO•2B2O3, occurring at 1038 K at the composition 34 mol%BaO-21 mol%ZnO-45 mol%B2O, L→BaO•2B2O3+BaO•4B2O3+ZnO•B2O3, occurring at 1008 K at the composition 19 mol%BaO-17 mol%ZnO-64 mol%B2O3.
The effects of halogenation treatments on the bond strength of the solid-state diffusion-bonded joint of tin have been investigated mainly by TEM observations of the interfacial microstructure. The halogenation treatment was carried out by exposing a tin surface (finished by grinding on emery paper) to a vapor of hydrochloric acid or hydrofluoric acid in a closed container. The halogenation treatments both by hydrochloric acid and by hydrofluoric acid decreased bonding temperatures by ~30 K at which bonded joints could be obtained and bond strength comparable with the base metal was achieved. TEM observations of the joint interface revealed that massive particles a few μm in size were distributed at the interface, when the halogenation treatment by hydrochloric acid was applied. The particle was identified as an amorphous phase consisting of Sn, Cl, and O on the bases of SAD patterns and EDX analyses. When the halogenation treatment by hydrofluoric acid was given to the surface, rodlike particles consisting of Sn, F, and O were observed at the interface. The rodlike particle was composed of crystalline SnO particles and an amorphous SnFx matrix. These particles consisting of Sn, X (=Cl or F), and O were much coarser and lower in number densities than the Sn-oxide inclusion observed when the halogenation treatment was not applied. As the bonding temperature was increased, the Sn-X-O particle coarsened and decreased in number densities, leaving the surrounding area with much smaller amounts of inclusions distributing in the tin substrate than those of the Sn-oxide observed at the joint interface bonded without the halogenation treatment. The formation and enlargement of the areas with much smaller amounts of inclusions in the interfacial region probably contributed to the increase in the bond strength at lower bonding temperature by the halogenation treatments.
It is possible to control the crystal alignment of non magnetic materials such as anisotropic ceramics and polymeric materials using a high magnetic field. However, alignment of the c-axis direction in hexagonal crystals, with a magnetic susceptibility of χc<χa=χb, is uncontrollable under a static magnetic field, because the c-axis can be in arbitrary direction in the plane perpendicular to the direction of the magnetic field. In this study, a high magnetic field and mold rotation are simultaneously imposed on a sample in order to align crystals parallel to the c-axis that has small magnetic susceptibility. This process was applied to hydroxyapatite crystals and a sample, in which the c-axis of the crystals aligned in a particular direction, was successfully obtained.
The shot peening process in normal conditions produces a compressive residual stress on the surface of a material without phase transformation. Instead, shot peening induces a change in phase (e.g. nanoferrite-layer and metal flow layer) on the surface of carbon steel under the intensified peening conditions associated with higher peening velocities and the use of a high-hardness shot media. This study investigated the effect of shot peening time on changes in surface microstructure and its effect on fatigue strength. The test specimens were compressive coil springs made from oil-tempered wire. The test springs were manufactured by the same process as that used for the test specimens except for the shot peening condition. A total of seven shot peening times were employed: 100, 300, 500, 1000, 2000, 3000, 6000 s. The projected material was 0.25 mm diameter steel cut wire. The test springs were measured for surface roughness and residual stress distribution observed using an optical microscope and scanning electron microscope. Fatigue tests were conducted using a spring fatigue test machine at a frequency of 30 Hz for 2×107 cycles and a test stress of τm±τa=600±540 MPa. Values of the residual stress distribution for 300-6000 s were similar, as was surface roughness of all the springs as peening was performed using the same media. The spring for the 300 s projection consisted of the matrix phase and the surface metal flow phase. Fatigue strength increased until a shot-peening time of 1000 s, after which levels remained constant. The spring microstructure for the 1000 s projection revealed a white layer on part of the surface. Durations exceeding 3000 s were associated with the occurrence of the white layer, which covered entire the surface and was not associated with any increase in fatigue strength.
The respective awareness of the Intergovernmental Panel on Climate Change (IPCC), the Japanese government, media and citizens about the change of sea level at some future date due to climate change was surveyed and analyzed. Three official reports from the IPCC, the white paper on the Quality of the Environment in Japan from the government, the articles in the Asahi Shimbun newspaper from about the past 20 years, and the questionnaires by the Japanese and local governments conducted towards citizens were used. The results of this investigation were that the IPCC concluded in their past three reports that the sea level was estimated to be lower because of ice in the polar regions due to climate change, the Japanese government did not describe this point clearly, the newspaper drew the opposite conclusion from the IPCC and the understanding of citizens was that the change in climate caused the sea level to rise. These differences were due to the lack of or misunderstanding of scientific knowledge such as Archimedes's Principle and the migration of fluid materials, and to the psychological trend of human beings. It is necessary for the government and media to clearly explain and announce these scientific facts in a modern society which maintains a close relationship to science.
The interfacial reaction between Sn-0.7 mass%Cu solder with Ni and a Cu substrate was investigated to reveal the effect of the addition of Ni to Sn-Cu solder on the microstructure of the interface. Sn-0.7Cu-xNi solders (x=0, 0.05, 0.1, 0.2 mass%) were used in this study. The results showed that, just after the reflow process at 523 K, the morphology of the intermetallic compound (IMC) formed between ternary Sn-0.7Cu-Ni solder and the Cu substrate is quite different from the intermetallic compound formed between binary Sn-0.7Cu solder and the Cu substrate. The added Ni converts the feature of IMC from a scallop morphology to a flat morphology. The Ni added to solder is contained in the IMC layer and the intermetallic phase between Sn-0.7Cu-Ni solder and Cu substrate can be expressed as (Cu1-y, Niy)6Sn5. On the other hand, the IMC thickness for Sn-0.7Cu-0.05Ni solder is the minimum in all solders regardless of aging time. Therefore it is found that the addition of 0.05%Ni to Sn-0.7Cu solder is certainly effective for reducing the formation of IMC layer at the interface during reflow process and for inhibiting the growth of IMC during the aging process.
Microstructural evolution taking place in pure copper during multi-directional forging (MDF) at 77 K and 300 K was studied. Samples were deformed up to total strain of 6.0 at maximum. At 300 K, the flow curve showed a rapid increase in flow stress at the early stage of deformation followed by steady-state flow at strains above 2. The microstructural change during deformation at 300 K was mainly characterized by the evolution of subgrains, the increase in the misorientation angles, and subsequently followed by evolution of ultra fine grains of the average size of 300 nm. In contrast, at 77 K, the flow curve showed a monotonic increase in the flow stress all strains. Deformation twins, which started to appear at high strains resulted formation of dense lamellar microstructures. The thickness of deformation twins was ranging from 10 to 100 nm. The obviously appeared twins contributed to grain refinement at 77 K. Microstructures evolved during MDF at both temperatures showed different annealing behavior. That is, static recrystallization onset earlier and spread more rapidly in the copper MDFed at 77 K than that at 300 K.
The effect of phosphorus addition on sulfide precipitation for strip casting low carbon steel containing copper was investigated and discussed with respect to the morphology, size and composition of sulfide. Both experimental results and mathematical calculation showed that the addition of phosphorus retards the sulfide precipitation at high temperature, promotes the supersaturation of sulfur and makes more copper bearing and smaller sulfide at low temperature. Phosphorus also promotes sulfide precipitation in α-Fe instead of in γ-Fe, so that with high cooling rate small and spherical copper sulfide forms instead of copper sulfide with a plate-like shape.
A plastic deformation process and ratio study of p-type Bi0.5Sb1.5Te3 was performed. The ingots were grown by the Bridgman method. Disks were cut from the ingots and deformed by either cold-pressing or hot-pressing under pulse current heating. The plastic deformation ratio was controlled in the range from 55 to 90%. The crystal structures of the deformed samples were identified by X-ray diffraction and pole figure analyses. The diffraction patterns indicate that the surfaces and bottoms of the samples were highly oriented in the hexagonal (00-l) plane. Thermoelectric properties change depending on not the plastic deformation ratio but the kind of plastic deformation process. The power factor for hot-press deformed samples exceeded those for the original ingots and cold-press deformed samples. The results suggest that the process of hot-press deformation enhances the thermoelectric properties of p-type Bi0.5Sb1.5Te3.
The life of creep crack growth for W strengthened 9-12%Cr steel is sensitive to the alloying additions and material structures, such as lath martensitic structure and grain size caused by inhomogeneous cooling rate in steel ingot during the manufacturing stage, which results in the large scattering of experimental data from the law of creep crack growth life. In this paper, creep crack growth tests were conducted using W strengthened 9-12%Cr steels with various contents of alloying additions and the dimensions of micro-nano structures. The effects of the composition of alloying additions and material structures on the life of creep crack growth for W strengthened 9-12%Cr steel were clarified.
Influences of electron beam irradiation on Charpy impact value of carbon fiber reinforced polymer (CFRP) have been investigated. The irradiation, which is one of short-time treatments, enhanced the Charpy impact value of CFRP. Furthermore, strengthening of carbon fiber, ductility enhancement of polymer and interface effects on impact test explains the impact value enhancement of CFRP.