通过作者查论文: Mayumi Suzuki

文章题目页数

作者: T. Kobayashi, Junichi Koike, Toshiji Mukai, Mayumi Suzuki, H. Watanabe, Kouichi Maruyama, Kenji Higashi
231
作者: A. Kumao, N. Nakamura, H. Endoh, Y. Okamoto, Mayumi Suzuki
567
作者: Mayumi Suzuki, Teiichi Kimura, Junichi Koike, Kouichi Maruyama
593
作者: Mayumi Suzuki, Akihiro Shibata, Kouichi Maruyama
摘要: The microstructures of thixomolded® (TM) Mg-Al-Ca alloys consist of α-Mg and eutectic compounds along grain boundaries. Misch metal (Mm) addition to TM Mg-Al-Ca alloys makes precipitates within α-Mg matrix and their number density and size depend on heat-treatment conditions. The small addition of Mm can keep the network-like grain boundary covering and the improvement of microstructure stability during creep. On the other hand, excessive Mm addition causes the deterioration of creep strength. The grain boundary coverage decreases with increasing Mm content due to the formation of coarse spherical Al-Mm based intermetallic compounds. Creep strength is significantly affected by both of the grain boundary coverage and the morphology of eutectic compounds along grain boundaries.
1249
作者: H. Sato, Mayumi Suzuki, Kouichi Maruyama, H. Oikawa
601
作者: Minoru Umemoto, Yoshikazu Todaka, Akifumi Ohno, Mayumi Suzuki, Koichi Tsuchiya
157
作者: Minoru Umemoto, Yoshikazu Todaka, Akifumi Ohno, Mayumi Suzuki, Koichi Tsuchiya
摘要: Dissolution behavior of cementite in eutectoid steels with pearlitic and spheroidite structures by severe plastic deformation was studied. Applying a long time milling, cementite dissolved completely and matrix turned out to be nanocrystalline ferrite. By a ball drop deformation (at high strain rates), heavily deformed layers in which cementite dissolves completely or partially were produced. By applying pulsed laser irradiation, re-austenitized zone which transformed to fresh martensite during quenching was produced. The boundary between the re-austenitized zone and matrix exhibited similar microstructure with that observed in specimens subjected to a ball drop deformation. It was suggested that the dissolution of cementite by heavy deformation at high strain rates are probably due to thermal effect, that is, re-austenitization.
461
作者: Hisaki Watari, Yoshimasa Nishio, Mayumi Suzuki, Toshio Haga, Keith Davey, Nobuhio Koga
摘要: A total weight reduction approach has been key issue for car manufacturers to cope with more and more stringent requirements for fuel economy. This paper describes the twin-roll casting technology of magnesium alloys that contain relatively high weight ratios of aluminum, such as AZ91,AZ101 and AZ111. The magnesium alloy sheets were cast by a horizontal twin roll caster to manufacture relatively high-strength Mg alloys with high aluminum content. The influences of such process parameters as casting temperature and roll speed were ascertained. The microstructures of cast magnesium alloy sheets were observed to investigate the effects of roll-casting conditions on crystal growth in the cast products. It was found that Mg alloys with high aluminum content can be fabricated at a roll speed of 15 m/min with a horizontal-roll caster. The grain size of the manufactured wrought magnesium alloy sheet was about 10 μm due to rapid solidification in the proposed process.
667
作者: Mayumi Suzuki, Kouichi Maruyama
摘要: Compressive creep behavior of hot-rolled (40%) Mg-Y and Mg-Y-Zn alloys are investigated at 480 ~ 650 K. Creep strength is substantially improved by the simultaneous addition of yttrium and zinc. The minimum creep rate of Mg-0.9mol%Y-0.04mol%Zn (WZ301) alloy decreases to 1/10 lower than that of Mg-1.1mol%Y (W4) alloy at 650 K. Activation energy for creep in W4 and WZ301 alloys are more than 200 kJ/mol at the temperature range of 480 ~ 550 K. These values are higher than the activation energy for self-diffusion coefficient in magnesium (135 kJ/mol). Many stacking faults (planar defects, PDs) are only observed on the basal planes of the matrix in Mg-Y-Zn ternary alloys. Stacking fault energy is considered to decrease by the multiple-addition of yttrium and zinc. The size and density of these planar defects depend on solute content, aging condition. TEM observation has been revealed that the decreasing of the stacking fault energy affects the distribution of dislocations during creep. Many a-dislocations on basal planes are extended significantly. Dislocation motion is restricted significantly by both of these two types of stacking faults (planar type and extended dislocations).
1602
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