Annealing behavior of the glow discharge decomposed amorphous Si (a-Si: H) covered with an evaporated Al layer has been studied by means of optical microscopy, scanning electron microscopy, transmission electron microscopy and electron diffraction.
The results are as follows;
(1) Electron diffraction from the Al surface exhibited that crystalline Si appeared on the Al surface by annealing at a temperature as low as 423 K.
(2) By annealing there appeared pits on the Al surface corresponding to growing crystalline Si on a-Si: H surface through the Al layer.
(3) At relatively low temperatures (below 473 K) the crystalline Si was preferentially formed along the grain boundaries of Al layer forming three dimensional networks ∼5 μm in diameter.
(4) At relatively high temperatures (above 523 K) the Al surface was covered with the crystalline Si, and the crystallization of Si also occurred along the grain boundaries of Al layer and on the a-Si: H surface.

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Graphite precipitation was investigated in Fe–Si–C powder compacts during carburization in hydrogen and vacuum. Nodular graphite was observed in sinter pores of binary Fe–C specimens after vacuum sintering without addition of any graphitizing element. Silicon generally promotes graphitization due to its cementite unstabilizing action, but Si-impurity segregations in sinter pores decreased the number and volume of pores, into which graphite could precipitate, and thus affected the morphology and distribution of graphite. Surface and internal oxidation of silicon on Fe–Si–C compacts influenced the C-diffusion during carburization and the morphology of graphite precipitates during cooling.

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The behavior of delayed failure in an air environment were investigated in ultra-high strength 18%Ni maraging steels. The slow crack growth rate caused by delayed failure increases with aging time in an early stage of aging, and after reaching a maximum, it decreases inversely with aging time. The aging time for the slow crack growth rate to reach a maximum becomes shorter with increasing aging temperature.
The delayed failure does not occur in vacuum environment, and therefore, it is assumed that the delayed failure is controlled by diffusion associated with stress-induced migration of hydrogen produced by decomposition of water adsorbed by the surface of the steel. The slow crack growth rate of the delayed failure depends on the catalistic action of steels changing with the aging condition which results in the decomposition of water.
The aging time for the slow crack growth rate to reach a maximum at respective aging temperatures is independent of the composition of the steels and only dependent on the aging temperature, but the slow crack growth rate depends on the chemical composition of the steels. Cobalt and titanium have a large effect on the slow crack growth rate, but molybdenum has little effect.
It is considered that the behavior of the delayed failure is controlled by the formation and decomposition of Ni₃Ti(DO₃) which probably promotes the decomposition of water.

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The effects of under-size alloying elements—V, Cr and Ru—and over-size alloying elements—Nb, Ti and Zr—on the workability and low temperature ductility of interstitial free molybdenum were investigated. The workability and ductility of the metal decreased with increasing alloy content, which was related to the atomic size misfit ratio of alloying elements to molybdenum.
The allowable amounts of alloy additions to obtain sound forgings at 1273 K were 1.5 mass% for vanadium, niobium and titanium, 1.0 mass% for ruthenium and chromium and 0.5 mass% for zirconium. The bend ductile-to-brittle transition temperature was kept under 163 K in the alloys with vanadium up to 0.7 mass%, ruthenium up to 0.5 mass%, chromium up to 0.3 mass%, niobium up to 0.5 mass%, titanium up to 0.3 mass% and zirconium up to 0.15 mass%.

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Carbon tends to suppress the grain boundary fracture of α-iron, which is promoted by the segregation of phosphorus and other impurities to grain boundaries. This effect of carbon is due to its grain boundary segregation. It is shown in the present paper that the same effect of carbon is observed when hydrogen promotes the grain boundary fracture. Iron specimens with and without carbon addition are tensile tested while being charged with hydrogen electrolytically at low temperatures. A specially prepared high purity iron fractures along grain boundaries after a few percent elongation when tested during hydrogen charging, otherwise it is completely ductile. The same iron is ductile even under hydrogen charging, if it is doped with carbon of about 20 mass ppm. The carbon effect is further investigated with fine grained specimens made from a commercial high purity iron. Tests are performed on as-quenched and on aged specimens with precipitates of ε-phase and Fe₃C. The results show that carbon segregated at grain boundaries has the effect to prevent the grain boundary fracture.

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The temperature dependence of yield stress and deformation substructure of directionally solidified eutectic composites of γ-γ′ (Ni–Al–Ti), γ′-α (Ni–Al–Mo) and γ-γ′-α (Ni–Al–Mo) alloys has been investigated. The yield stress of these alloys shows the positive temperature dependence, which is the characteristics of γ′ (Ni₃Al) alloy, and attains peak values at about 973 K. Above 973 K, the recovery takes place and the alloys soften. At room temperature deformation of the γ and γ′ phases begins earlier than that of the Mo fibers, but at higher temperatures all the phases are deformed at relatively small strain. The origin of the characteristic dislocation structure of deformed composites and the contribution of each phase to the strength of the composites are discussed.

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Commercially pure iron, S45C, Fe–Cr, Fe–Si and Fe–C alloys were dipped into molten aluminium (99.8%) mostly at 1073 K and rotated at various speeds for various times. Then an alloy layer formed on each alloy was examined, and the dissolution process of these alloys was studied. The thickness of the alloy layers became thinner with increasing rotating speed. With regard to the composition of the alloy layers, Fe₂Al₅ occupied the major portion in the same manner as under the static condition. The shape of the alloy layers formed on commercially pure iron, Fe–Cr and Fe–Si alloys changed from tongue-like to band-like, as the rotating speed increased. For Fe–C alloy, the alloy layer is band-like at every rotating speed.
The dissolution rate of each alloy layer increased, as the rotating speed increased. As under the static condition, the dissolution resistance against molten aluminium is the highest in Fe–C alloy and the lowest in Fe–Si alloy. The dissolution process of commercially pure iron, S45C, Fe–Cr and Fe–Si alloys is controlled by the diffusion of Fe in molten aluminium. Moreover, in commercially pure iron, Fe–Cr and Fe–Si alloys, the dissolution is accelerated by natural convection and flaking of the alloy layer at lower rotating speed, while, at higher rotating speed, it is accelerated by flaking of the alloy layer and mechanical erosion due to molten aluminium or by turblent flow near the rugged surface of alloys. The dissolution of Fe–C alloy, however, was controlled by the chemical reaction or mass transfer in the alloy layer and the diffusion of Fe in molten aluminium.

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The impact of process parameters like temperature, the dimension and the position of an impeller on the incorporation of Al₂O₃ particles in cast Al–Mg alloy has been investigated. The maximum incorporation level of Al₂O₃ particle is achieved by dispersing the Al₂O₃ particles in the semi-solid alloy by the impeller with a diameter 0.63 times as large as that of the crucible at stirring speed of 16 revol. s⁻¹. The optimal position of the impeller has been found to be 0.81 times as large as the depth of the liquid at rest from the bottom of the crucible. Incorporation of Al₂O₃ particles increased with the decrease of melt temperature between the solidus and the liquidus temperature under given stirring speed, dimension and position of the impeller. Model experiments have been conducted with water and poorly wetting plastic beads, in order to find an explanation for the role of the above variables. An estimate of the porosity in the cast alloy indicates a linear increase with the amount of Al₂O₃ particles incorporated.

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