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Volume 44, Issue 3
Displaying 1-12 of 12 articles from this issue
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Ichiro KAWAHARA, Masaya NAKAGAWA, Naritoshi AOYAGI, Yo KOJIMA1994 Volume 44 Issue 3 Pages 129-135
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe tensile strength in parallel direction (parallel-TS) and in perpendicular direction (perpendicular-TS) to woven fiber surface of woven SiC continuous fiber reinforced aluminum alloy composites were investigated. The composites were fabricated by melt infiltration process using a die casting. Effect of fiber volume fraction (Vf), fiber orientation angle (θ), and a heat treatment temperature in vacuum on strength were also examined and discussed. Parallel-TSs of the all composites are superior to that of matrix metal. The fiber orientation angle affects the parallel-TS of composites. When orientation angle is over 30 degree, the parallel-TSs are significantly decreased. Perpendicular-TS under as-cast condition was approximately 12MPa. Parallel-TS and perpendicular-TS in the composites with Vf2%, θ=0, gradually decreases at heat treatment temperature up to 350°C, however, in case of the heat treatment at 500°C, these strength significantly increases. The fiber pull-out was observed in fracture surface after tensile test in parallel direction under ascast condition, and the fracture surface of specimen after heat treatment at 500°C tends to be flatter with less fiber pull out. It is considered that tensile strength in parallel direction depend on the matrix strength and that in perpendicular direction depend on the adhesive strength.View full abstractDownload PDF (2193K) -
Toshio HAGA, Mitsugu MOTOMURA, Arman MUNAF, Shinsuke SUZUKI1994 Volume 44 Issue 3 Pages 136-141
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThis study was done to define the casting property of aluminum alloy strip by the melt drag process. Roll speed, roll material, melt-height in the nozzle (roll-molten metal contacting length) and nozzle position for roll were chosen as fundamental formation factor and investigated. Sound strip is cast in the range of 20-70m/min, and thickness of the strip was 0.5-1.5mm. Strip thickness can be controlled by roll speed and contacting length between roll and molten metal. Strip thickness increases with decrease of roll speed and increase of roll-molten metal contacting length. Diagram, by which we can estimate the dependence of such fundamental factors as roll speed, melt-height in the nozzle on the thickness and quality of the strip, is drawn. Surface condition and thickness distribution of the cross section of the strip depend on contacting condition between roll and molten metal (strip). Aluminum coating on the roll surface is useful for getting sound contacting condition between roll and molten metal (strip).View full abstractDownload PDF (1599K) -
Akihisa INOUE, Katsumasa OHTERA, Akihisa INOUE, Tsuyoshi MASUMOTO1994 Volume 44 Issue 3 Pages 142-146
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSHigh-strength aluminum alloys have attracted increasing interest because of a possibility of reducing the weight and volume of constructional materials. This paper aims to report that the warm extrusion of rapidly solidified powders in Al-Ni-Ti and Al-Ni-Zr systems causes simultaneous achievement of high tensile strength and good ductility. The atomized powders consist of a mixed structure of Al and Al3Ni crystals. The structure in the warm-extruded alloys changes to Al+Al3Ni+Al3Ti(L12) +Al3Ti(D022) for Al-8at%Ni-3.5at%Ti alloy and Al+Al3Ni+Al3Zr(L12)+Al3Zr(D023) for Al-8at%Ni-2.5at%Zr alloy. The grain size of the aluminum matrix is about 150nm and the size and spacing of particles are about 60nm and 70nm, respectively. The extruded bars exhibit tensile strength of 865MPa, Young's modulus of 106GPa and fatigue strength of 350MPa at 107 cycles at room temperature. These excellent mechanical properties are presumably due to the dispersion strengthening of fine intermetallic compounds and the strengthening due to the grain size refinement of aluminum matrix.View full abstractDownload PDF (1288K) -
Toshikatsu ASAHINA, Kazuyoshi KATOH, Hiroshi TOKISUE1994 Volume 44 Issue 3 Pages 147-151
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSAZ31 magnesium alloy was friction welded using a brake type friction welding machine under optimum welding conditions such as P1=50MPa, t1=5s, P2=100MPa and t2=5s. The fatigue tests were conducted by Ono's rotary bending tester for smoothed and notched specimens and Shenck type repeated torsion fatigue tester for smoothed specimen. In the rotary bending tests on the smoothed specimen, both fatigue strength and fatigue ratio of the welded joints are lower than those of the base metal irrespective of the number of cycles. Fatigue limit of the welded joint is 81.4% of the base metal. Fatigue strength of the welded joints with notch at the weld interface is slightly lower than that of the base metal. Fatigue limit of the welded joint is 93.1% of the base metal. The notched specimens show fatigue limit lower values than smoothed specimen for both base metal and welded joint. In repeated torsion fatigue tests, the fatigue strength at given endurance of welded joints decreased almost in a linear manner with increase of the number of cycles. Fatigue limit of the welded joint is 95.8% of the base metal. Without exceptions, smoothed specimens fractured at the weld interface regardless of the method of tests. In case of same fatigue test, the smoothed specimens of welded joint show nearly equal macro- and microfractographs independent of the number of cycles to failure.View full abstractDownload PDF (1179K) -
Shigeoki SAJI, Keiichi HIRAO, Toshimi YAMANE, Masashi MEHATA, Takamasa ...1994 Volume 44 Issue 3 Pages 152-157
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSMicrostructure, fatigue properties, tensile strength, density and phase identification have been investigated for sintered compacts of TiAl base intermetallic compound powders prepared by combustion synthesis from pure titanium and aluminum powders. The results obtained are as follows: Both the TiAl powder prepared by the combustion synthesis and the compacts sintered at 1523-1648K for 25.2ks consist of γ-TiAl and α2-Ti3Al. The microstructure of the sintered compacts is dependent on the sintering temperature. The compacts sintered at 1523 and 1553K show equiaxed grains of the γ-and α2-single phase, and the compacts sintered at 1573 and 1648K contains α2/γ lamellar grains in addition to the γ-and α2-single phase grains. The amount of voids in the sintered compacts decreases with increasing sintering temperature and the relative density increases with increasing sintering temperature. The compact sintered at 1523K which contains most voids shows the lowest fatigue strength and the compact sintered at 1553K consisting of the (γ+α2) fine microduplex structure shows the highest fatigue strength. Preferential nucleation of cracks at theα2/γ lamellar interfaces in the compacts sintered at 1573 and 1648K brings about decrease in fatigue strength. The ratio of fatigue strength (at 107 cycles)to the tensile strength (UTS) is about 0.6 to 1.0, and decreases with increasing temperature. Large value of the fatigue ratio is characteristic of TiAl base intermetallic compounds.View full abstractDownload PDF (1315K) -
Kinji SATO, Toshio YOKOYAMA1994 Volume 44 Issue 3 Pages 158-163
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSA concentric circular groove is on the both end surfaces of aluminum alloy column to retain lubricant. The columns are compressed by appling lubricant oozed from a groove and its barreling forms are measured. Effects of diameter and depth of concentric groove on the lubricating ability are studied in the compressibility of 10 to 40%. Effective geometric conditions of a groove are obtained from these experiments. Material flow patterns in the cross section of compressed columns with a concentric groove is shown in the comparison with a compressed column without a groove.View full abstractDownload PDF (880K) -
Shin-ya KOMATSU, Masahiko IKEDA, Yoshiaki TABATA, Takehisa GOUDA1994 Volume 44 Issue 3 Pages 164-170
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSThe relations between the ratio of resistance measured at two different temperatures and the resistivity are induced for general solid solutions showing deviation from Matthiessen's Rule (DMR) through dependences of resistivity on concentration and on temperature. The contribution to resistivity per unit concentration (Δρ) of Mg has been experimentally determined at 77 and 300K. The Δρ is larger at higher temperature and the DMR is slightly positive. After a correction about DMR, the empirical relation between the resistance ratio (R=ρ(300)/ρ(77)) and the resistivity at 77K (ρ(77)) has been obtained as
2.3<ρ(77)/nΩm=[25.15/(R-1.054)]-0.028<23
in the solution treated state. Comparing the Matthiessen empirical relation of cold rolled specimens to that of annealed specimens, the DMR of dislocation in aluminum is estimated to be negative.View full abstractDownload PDF (859K) -
Ryuji NINOMIYA, Hiroshi YUKAWA, Masahiko MORINAGA1994 Volume 44 Issue 3 Pages 171-177
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
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Hisashi TAKEUCHI1994 Volume 44 Issue 3 Pages 178-188
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
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Shouichi TAKAYAMA1994 Volume 44 Issue 3 Pages 189-191
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (305K) -
Yoshio KATO1994 Volume 44 Issue 3 Pages 192-193
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (261K) -
Shigeharu KAMADO1994 Volume 44 Issue 3 Pages 194-196
Published: March 30, 1994
Released on J-STAGE: October 30, 2008
JOURNAL FREE ACCESSDownload PDF (330K)
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