巻号一覧
76 巻, 10 号
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福江 正浩, 吉年 規治, 山田 類, 川崎 亮2012 年 76 巻 10 号 p. 573-578
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーFe based metallic glassy alloys are prospective material for micro parts due to their excellent mechanical properties. In this study we successfully prepared two kinds of [(FeXCo1−X)0.75Si0.05B0.2]96Nb4 (X=0.5 and 0.8) alloy mono-sized spherical particles with various sizes as a raw material for the micro parts by using originally developed process named Pulsated Orifice Ejection Method. Each alloy exhibits different critical diameter for maintaining a glassy phase due to the different glass forming ability. We estimated the critical cooling rates of X=0.5 and 0.8 alloys to be 1000 K/s and 4000 K/s, respectively from calculation of cooling process during the free fall of the molten alloy droplets in cooling gas. Oxygen contamination amounts of the obtained particles are also investigated for the comparison between the conventional casting process and our new process.
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土田 紀之, 井上 忠信, 榎並 啓太郎2012 年 76 巻 10 号 p. 579-586
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーTrue stress (σ)-true strain (ε) relationships until just before fracture, i.e., the plastic deformation limit, were estimated by the stepwise tensile test and the Bridgman equation for various metals and alloys with different crystal structures. The estimated σ-ε relationships were different from the nominal stress-strain curves including the conventional tensile properties. In the relationships between the true stress (σpdl) and true strain (εpdl) at the plastic deformation limit, SUS304 and SUS329J4L indicated a better σpdl-εpdl balance. On the other hand, SUS329J4L, tempered martensite, and an ultrafine-grained steel showed superior results in the yield strength-εpdl balance. The estimated σ-ε relationship for the ultrafine-grained steel suggests that grain refinement strengthening can improve σ and ε up until the plastic deformation limit. The value of εpdl became larger with increasing the reduction in area and a decrease in the fracture stress. The products of σpdl and εpdl became larger with increasing work-hardening rate at the plastic deformation limit.
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土本 憲太郎, 湯川 宏, 南部 智憲, 松本 佳久, 湯川 伸樹, 石黒 太浩, 村田 純教2012 年 76 巻 10 号 p. 587-590
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーThe alloying effects of tungsten (W) and molybdenum (Mo) on the mechanical properties of niobium (Nb) have been investigated by means of Vickers hardness test and cold upsetting test. It is found that the alloying effects of W and Mo on the Vickers hardness for the as-cast samples are nearly the same and the hardness increase almost linearly with increasing the total amount of alloying elements, W and Mo. The compressive yield stress of the binary and ternary alloys also increase almost linearly with increasing the amount of the alloying elements into Nb. On the other hand, the alloying effects of W and Mo on the work hardening behavior of the alloys appear to be different. For example, the flow stress of Nb-5 mol%W alloy is higher than that of Nb-5 mol%Mo alloy after yielding in the upsetting test. In fact, the work hardening exponent, n, in the power low is larger for Nb-5 mol%W alloy than Nb-5 mol%Mo alloy.
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寺門 修, 岩城 大輔, 村山 恭平, 平澤 政廣2012 年 76 巻 10 号 p. 591-596
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーIn the focus of selective recovery of indium from waste flat panel display, we have studied chlorination treatment where ammonium chloride, NH4Cl, has been used as chlorination reagent. Glass plate on which ITO is deposited, denoted hereafter as ITO glass, has been employed as model sample. It was found that indium could be successfully recovered from ITO glass in the form of volatile indium chloride by heating the mixture of ITO glass and NH4Cl at the temperature above 400℃ under inert atmosphere. The influence of process parameters, such as treatment temperature, milling condition of ITO glass and composition of NH4Cl, was investigated in order to achieve high process efficiency.
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高木 秀有, 道 明, 藤原 雅美2012 年 76 巻 10 号 p. 597-606
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーIndentation creep tests and finite element simulations were performed on a model material to show that a constitutive equation for conventional uniaxial creep can be derived using the instrumented indentation testing technique. When the indentation pressure and the indentation creep rate maintain constant values of ps and εin(s), respectively, the contours of the equivalent stress and the equivalent plastic strain rate in the region beneath the conical indenter expand according to the increase in the indenter displacement while maintaining the geometrical self-similarity. These findings indicate that a pseudo-steady state deformation takes place around the indenter tip. The representative point exhibiting the creep behavior within the limited region, which actually determines the indenter velocity, is defined as the location where the equivalent stress σr is equal to ps/3. The equivalent plastic strain rate εr at this point is found to be εin(s)/3.6 in the case that the creep stress exponent is 3. The stress exponent and the activation energy for creep extracted from the results of Al-5.3 mol%Mg solid-solution alloy indentation tests are in close agreement with those of tensile creep tests reported in the literature. In addition, the values for σr and εr agree well with the values for the applied stress and the corresponding creep rate in tensile creep tests at the same temperature. The above results show not only that the creep characteristics of advanced materials, which are often available in minute quantities or as small-volume specimens, can be obtained from carefully designed indentation creep tests, but also that the constitutive equation for tensile creep can be predicted with sufficient precision through indentation creep test results.
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木村 彩香, 有馬 義貴, 南部 智憲, 湯川 宏, 松本 佳久2012 年 76 巻 10 号 p. 607-613
発行日: 2012年
公開日: 2012/10/01
ジャーナル フリーThe alloying effects of group 5 and 6 metals on the durability for Pd-based hydrogen permeable membranes are investigated systematically. The surface defects, so called Kirkendall voids, that cause a gas leakage, are formed around iron particles adhered on the Pd-based metal membrane during hydrogen permeation reaction. It is found that the formation of these surface defects are inhibited by the addition of only 1 mol% of group 5 or 6 metals into palladium in hydrogen atmosphere at less than 873 K. The growth rate of the crystal grain of Pd-20 mol%Ag-1 mol%W alloy is slower than Pd-22 mol%Ag alloy at 973 K, indicating that the inter-diffusion of metal atoms is delayed by the addition of tungsten into palladium. The vacancy formation energies of metals increase almost linearly with their melting temperatures. Thus, it can be understood that the improvement of the durability against the iron particles may attributable to the decrement of the inter-diffusion rate through the modification of the vacancy formation energy by the addition of group 5 or 6 metals into palladium.
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