Charpy type impact test, hardness measurement, optical and transmission electron microscopy were performed with Fe–P alloys (P, 0.05, 0.1, 0.5 and 1.0 mass%) containing various amount of carbon (0.001 to 0.18 mass%). The fracture surface was examined by Auger electron spectroscopy to measure the degree of segregation of phosphorus and carbon. Specimens were quenched into oil from 1123 K or 1173 K.
Phosphorus increases the ductile-brittle transition temperature both in intergranular and transgranular fracture mode, and carbon tends to suppress the intergranular fracture. The optimum carbon concentration to improve the toughness is 0.01%. Carbon above this concentration causes the formation of pearlite nodules during quenching and the toughness decreases.
Discussion was made on the mechanisms proposed to explain the effect of carbon to suppress the intergranular fracture. Any theory which assumes an interaction between carbon and phosphorus atoms at grain boundaries seems to have difficulties. Although more researches are needed, the hypothesis considering carbon by itself to improve the grain boundary cohesion seems to be promising.

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The FCC to FCT transformation in Mn–22 at% Cu and –26 at% Cu alloys has been examined by means of X-ray diffraction and optical and electron microscopies with a cooling stage. The c parameter and the c⁄a ratio of the FCT martensite decrease with decreasing temperature, abruptly below the transformation temperature and then very slowly, showing a characteristic of the second order type phase transformation. On the other hand, the optical microscopy shows a coexistence of untransformed and transformed regions, exhibiting a characteristic of the first order type phase transformation. Banded relief is observed in the transformed region, which corresponds to the formation of tetragonal twins. No internal structure as lattice invariant shear is observed in the banded twins even by electron microscopy. The banded region expands and the relief contrast increases with decreasing temperature. Correspondingly, the electron microscopy exhibits lamellar contrast below the transformation temperature. However, very fine striations appear prior to the lamellar appearance. Both the lamellar and striations are parallel to {011} planes of the FCT martensite, and are supposed to be tetragonal twins introduced to reliese a tetragonal distortion due to the FCC to FCT transformation and the magnetic transformation, respectively. The temperature difference between the structural and magnetic transformations is about a few of ten degrees, being in agreement with that in a previous work.

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Single crystals of high-purity (RRR\simeq4000) niobium were tested in tension in the temperature range of 2 K–350 K to study the low temperature plasticity. Activation analyses of the results showed that an Arrhenius type strain-rate equation appeared to hold above 50 K but not below this temperature. Increase of the flow stress with the superconducting to normal transition by application of magnetic field changed almost linearly with decreasing temperature below the critical temperature (9.3 K).
Experimental data of activation analyses below 70 K for four bcc metals, present Nb, previous Ta, Fe and β-CuZn (CsCl type), exhibit a common feature of discrepancy of the Arrhenius rate equation at very low temperatures. The mechanism of this discrepancy has been discussed in terms of quantum mechanical vibration of dislocations.

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In order to determine the activity coefficients of oxygen, γ_O, in liquid Cu–Tl alloys at 1373 K as a function of alloy composition, the modified coulometric titrations described previously have been performed by using an electrochemical cell: O in liquid Cu–Tl alloys/ZrO₂(+CaO)/Air, Pt. The activity coefficients of oxygen in liquid copper and thallium are considerably lowered by a little addition of thallium and copper respectively so that a deep upwardly concave curve of lnγ_O vs alloy composition is suggested over the entire composition range of Cu–Tl alloys. The interaction parameter of thallium on oxygen is evaluated to be −7.5 at 1373 K . The present results have been compared with the calculated values based on solution models.

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The bend deformation characteristics of WC–Co cemented carbides were investigated in the temperature range from room temperature to 1273 K by measuring load-deflection curves and examining the structural change due to deformation, in relation to cobalt content, tungsten carbide particle size, domain (grain) size of binder phase and carbon content. The cemented carbides were almost elastically deformed up to fracture at room temperature, but they became to be plastically deformed at high temperatures above about 873 K . The high temperature deformation, however, was not composed merely of a true plastic deformation, because stable cracks were frequently formed at high stress levels. Effects of the above factors on the deformation characteristics at temperatures below 873 K can be explained mainly from the viewpoint that the binder phase is dispersion-hardened and solid-solution hardened. However, the effects of particle size and carbon content at high temperatures tended to be reverse to those at low temperatures. This is explained by the dynamic recovery of binder phase occurring at high temperatures. The deformation at high temperatures and high stress levels was found to be suppressed with increase in domain size. In this paper, the relation between transverse-rupture strength and deformation characteristics was also briefly mentioned.

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Deformation and fracture behaviors of metastable β-Ti alloys (Ti–15Mo–5Zr and Ti–15Mo–5Zr–3Al) have been investigated. Large elongation in as-quenched Ti–15Mo–5Zr results from an appropriate combination of {332}⟨113⟩ twinning and ⟨111⟩ slip. Although mechanical twinning is suppressed by initial aging, considerable ductility is attained in Ti–15Mo–5Zr hardened by such aging at 573 K for 1.2 ks that ω-phase is precipitated. The reduction in macroscopic ductility on further aging could be related to an inhomogeneous slip. Embrittled Ti–15Mo–5Zr exhibits a ductile, dimple type fracture surface. On the other hand, mechanical twinning is not induced in as-quenched Ti–15Mo–5Zr–3Al, although large elongation is obtained. Ti–15Mo–5Zr–3Al is remarkably embrittled by precipitation of α-phase on aging at 623 K. As-quenched or embrittled Ti–15Mo–5Zr–3Al shows a mixture of an intergranular fracture surface and a dimple type fracture surface. The ductility of the present metastable β-Ti alloys is discussed in comparison with other metastable β-Ti alloys.

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The internal friction Q⁻¹, the magnetic hysteresis loop, the magnetostoriction λ, ΔG effects and mechanical properties have been measured for Ni–Co alloys containing 0–70% Co. The Q⁻¹ and regidity modulus measurements were carried out by the inverted tortion pendulum method. The hysteresis loop and λ were measured using an automatic recording fluxmeter and the optical roller method. Tensile testing was performed using an Instron-type tensile machine.
The Q⁻¹ values of Ni–Co alloys increase with maximum amplitude of shear strain γ_m and attain their peaks Q_max⁻¹. For the alloys with less than 20% Co, the variation in Q_max⁻¹ with Co content is complex and Q_max⁻¹ shows a maximum at 10% Co. For the alloys with more than 22% Co, Q_max⁻¹ becomes higher by water-quenching than by furnace-cooling.
In the range of 20–60% Co, the hysteresis loop after furnace-cooling is of the Perminvar-type, but the one after water-quenching is normal. Forthermore, variations in the coercive force H_c with Co content and heat-treatment are very similar to those in γ_c where γ_m corresponding to Q_max⁻¹. The H_c value is proportional to the γ_c value. The strengths of magnetic field H for the peak of Q_max⁻¹ are almost consistent with those for the maximum values of ΔW_h⁄ΔH and Δλ⁄ΔH which are gradients of lines joining the origin to each point on the curves of hysteresis loss W_h and λ versus H.

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