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Volume 35, Issue 8
Displaying 1-8 of 8 articles from this issue
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Tsuneo SAITOH1985 Volume 35 Issue 8 Pages 437-438
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (362K) -
Akihiko KAMIO, Hiroyasu TEZUKA, Tatsuo SATO, Than Trong LONG, Tsuneo T ...1985 Volume 35 Issue 8 Pages 439-446
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSAl-0.5 to 4mass%Ce, Al-1 mass%Fe-0.5mass%Ce and Al-4mass%Fe-4mass%Ce alloys were rapidly solidified into a ribbon shape at 105 and 106K/s by a single roller technique. The solid solubility of Ce in aluminum cooled at 106K/s extends up to about 0.5mass%. A spherical metastable phase which probably has f.c.c. structure a=0.828nm is observed in the ribbons containing Ce 1 to 4mass%. Coarse spherical particles and cell structures form at a cooling rate about 105K/s. The spherical particles and cell boundary intermetallic compounds have an orthorhombic structure with a stoichiometry corresponding to the equilibrium Al4Ce phase. Al-4mass%Fe-4mass%Ce alloys solidified at 106K/s contain fine particles of Al-Ce metastable phase. When these alloys and the alloy containing supersaturated solid solution are heated at 673K for 3.6ks, a plate shaped Al-Fe-Ce metastable phase precipitates in the <100> direction of the matrix. This phase probably has a cubic structure with an unit cell parameter a=0.410nm. Al-Fe-Ce metastable phase precipitated in the α-cell and the cell boundary intermetallic compound in the alloy cooled at 105K/s have a tetragonal structure with a stoichiometry corresponding to the equilibrium Al8CeFe4 phase.View full abstractDownload PDF (3880K) -
Hiroshi MABUCHI, Yutaka NAKAYAMA1985 Volume 35 Issue 8 Pages 447-454
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSPlane bending fatigue tests on polycrystalline Al-5%Mg alloys were carried out at elevated temperatures up to 500°C. A remarkable drop in fatigue life at a constant plastic strain amplitude is observed in the intermediate temperature range which depends on cyclic frequency and grain size. Transgranular crack initiation occurs at room temperature. Significant intergranular crack initiation and growth occur at elevated temperatures. Squared-up grain structure by grain boundary migration which leads to clear intergranular cracking is observed at higher temperatures. The transition from transgranular to intergranular fractures is satisfactorily explained in terms of the accumlation of grain boundary sliding. A drop of fatigue life is associated with the intergranular fracture, while grain boundary migration at higher temperatures is closely related with the recovery of fatigue life.View full abstractDownload PDF (2695K) -
Ryoji MISHIMA, Hitoshi MIYAMOTO, Nobuyuki MATSUZOE1985 Volume 35 Issue 8 Pages 455-462
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSEutectic Al-12%Si, Al-13%Mg2Si and Al-6%Ni alloys, Al-Mg-Mn-Cr, Al-Mn and Al-Mg-Si-Mn-Cr alloys were directly rolled from the liquid state between rotating twin chill rolls into plates 6mm in thickness and were cold rolled into sheets about 1mm in thickness. Bulge forming superplasticity tests were carried out. Eutectic particles are uniformly refined and transition elements effective to obstruct recrystallization are supersaturated to a greater degree in the sheets solidified at high cooling rates 300 to 600K/s. Such sheets are preferable in superplasticity to the usual sheets. Refined eutectic particles in the alloys having low volume fraction of eutectic particles play an important role in obstructing coarsening of recrystallizaed grains similarly as precipitates. The sheets containing such particles stable at elevated temperatures as Mg2Si have excellent superplasticity even at higher temperatures. Delayed transformation of the particles at elevated temperatures is effective to keep the superplastic condition.View full abstractDownload PDF (2860K) -
Kenji MATSUKI, Shuichi TAKATA, Mitsugu TOKIZAWA1985 Volume 35 Issue 8 Pages 463-470
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSA Zn-22wt%Al alloy was superplastically compressed with or without ultrasonic oscillations under various deforming conditions. The nominal stress (σ) increases with increasing strainrate (ε) and strain (ε) especially in a higher strain range. σ remarkably reduces and specimen temperature during compression elevates with increasing ultrasonic amplitude by applying ultrasonic oscillations. A decrease in σ by applying ultrasonics (Δσ) is more significant as ε and. ε increase and the initial specimen has less heights. The specimen temperature rapidly rises after appliciation of ultrasonics and saturates with increasing ε. The visioplasticity analysis shows that the restrained zone of superplastic flow is formed due to the friction across the die and that application of ultrasonics is effective to reduce the frictional restraint during deformation in the lower strain rate range and to accelerate the superplastic flow in the higher strain rate range. The decrease of frictional constraint and temperature rise contribute to the decrease of σ with application of ultrasonics. Improvement of the superplastic deformability in connection with grain boundary and phase boundary relaxation also contribute to the decrease of σ.View full abstractDownload PDF (1416K) -
Kenji MATSUKI, Shuichi TAKATA, Mitsugu TOKIZAWA1985 Volume 35 Issue 8 Pages 471-477
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSSuperplastic Zn-22wt%Al alloy was extruded by close-die sets with three types of punch to which ultrasonic oscillations are applicable. The extrusion load(W)is related to the extrusion speed(V)by the equation W∝Vm". The values of m" generally 0.4 to 0.5 are comparable to those of strain rate sensitivity index m in superplastic deformation in tension or compression. In the extrusion condition in which severe frictional restraint arrises, however, m" decreases down to 0.3 or less. If ultrasonic oscillations are applied, the extrusion load decreases, and m" does not decrease even in the extrusion condition described above. Application of ultrasonic oscillations is effective to flatten the top shape of specimens and to increase the extrusion speed at a constant load. The degree of extrusion load and increase of extrusion speed by applying ultrasonic oscillations are mainly due to the decrease of frictional constraint.View full abstractDownload PDF (1070K) -
Akihiko KAMIO1985 Volume 35 Issue 8 Pages 478-484
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
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Takakado NAKAYAMA1985 Volume 35 Issue 8 Pages 485-498
Published: August 31, 1985
Released on J-STAGE: July 23, 2008
JOURNAL FREE ACCESSDownload PDF (2044K)
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