Journal of Japan Institute of Light Metals
Online ISSN : 1880-8018
Print ISSN : 0451-5994
ISSN-L : 0451-5994
Volume 47, Issue 8
Displaying 1-8 of 8 articles from this issue
RESEARCH REPORT
  • Ming YANG, Hisashi NISHIMURA
    1997 Volume 47 Issue 8 Pages 415-420
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    The formability is evaluated by a tensile test and several deep drawing tests. The tensile test of the sheet carried out at room temperature with strain rates ε=0.01 to 20 indicates that the elongation increases with increase in strain rates. It is also found that the elongation is strongly related to the occurrence of serration during the deformation. The press formability of the sheet is further evaluated by a circular cup deep-drawing test with various strain rates and lubricants. The effects of strain rate on the press formability and lubrication are classified and the proper press forming condition for the aluminum alloy is obtained.
    Download PDF (715K)
  • Susumu IKENO, Kenji MATSUDA, Takeshi TERAKI, Seichi RENGAKUJI, Fujio S ...
    1997 Volume 47 Issue 8 Pages 421-426
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    Aging process of Al–1.0 mass%Mg2Si alloy composite materials with 4 vol% and 8 vol%SiC particles was investigated by micro-Vickers hardness measurement and transmission electron microscope observation. When SiC particles are dispersed into the Al–Mg–Si alloy, aging time to reach the maximum hardness is shortened at 473 K. The over-aged composite material with 4 vol%SiC particles includes various kinds of metastable phase precipitates; namely β' phase, the TYPE–B and TYPE–C precipitates of which crystal structures are different to each other. Fractions of these three kinds of precipitates in the composites are the same as in the mother alloy containing 0.2 mass% excess Si. The composite material with 8 vol%SiC particles contains the TYPE–A, TYPE–B and TYPE–C precipitates, but is free from β' phase precipitates. The existence of those precipitates has correspondingly been observed in the mother alloy containing 0.4 mass% excess Si. The estimation that the oxide (SiO2) layer must have formed on the surface of each SiC particle with the maximum thickness of about 17 nm can be deduced from the assumption that a considerable portion of excess Si originates from the oxide layer on the surface of SiC particles in the composite materials.
    Download PDF (1655K)
  • Satoru ISHIHARA, Mikio KONDOH
    1997 Volume 47 Issue 8 Pages 427-433
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    Al–17 mass%Si–4.5 mass%Cu–0.5 mass%Mg rapidly solidified powder metallurgy (RSP) alloy was prepared by hot extrusion method. High temperature tensile property of the alloy was investigated in the temperature range from 400 to 540°C. Typical superplastic behavior was observed at 500 and 520°C. The value of the maximum tensile elongation of the alloy tested at 500°C was about 380% with an initial strain rate of 10−2s−1. At 520°C, partial melting phenomena by solute segregation at some grain boundaries were induced, and the maximum elongation of about 390% was obtained at higher initial strain rate than the case at 500°C of 10−1s−1. The superplastic behavior at both the temperatures may be based on grain boundary sliding and accommodation mechanism. At 520°C, the liquid phase at grain boundaries may play the role of an accommodation helper, absorbing dislocations and relieving the stress concentration due to sliding.
    Download PDF (1169K)
  • Yoshiaki KAWAGUCHI, Junichi KANEKO, Makoto SUGAMATA
    1997 Volume 47 Issue 8 Pages 434-439
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    With a purpose of increasing the mechanical strength of Al–Si based casting alloys, a ball milling treatment was applied to the rapidly solidified flakes and machined chips. The ball milling was carried out by using an attritor ball mill with addition of methanol as the process control agent. The P/M materials were produced from the ball milled powders by hot extrusion and their structures and mechanical properties were compared with those prepared without ball milling. Attained increases in tensile strength by the ball milling treatment of the rapidly solidified flakes are about 400 MPa for the hypoeutectic and eutectic Al–Si based alloys and less than 250 MPa for the hypereutectic alloy. The strength increases by ball milling are generally much larger than those obtained by rapid solidification. The highest tensile strength of 776 MPa is observed for the rapidly solidified and subsequently ball milled material of the JIS AC8A (ASTM 336.0) alloy. Strengthening attained by ball milling is explained by highly stabilized work hardened substructures due to fine dispersoids formed during ball milling.
    Download PDF (1052K)
  • Kimiyoshi KITAZAWA, Masakatsu NAKANE
    1997 Volume 47 Issue 8 Pages 440-445
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    For incremental stretch-expanding of sheet metal, the reduction of tool-path schedule is recognized because numerous tool-paths are generally necessary for producing the required profile. A suitable tool-path schedule has been found for hemispherical shells, but the tool-path schedule for hemi-ellipsoidal shells has not been solved yet. In order to reduce the tool-path schedules for producing the hemi-ellipsoidal shells, a possibility of two path method in which a hemi-ellipsoidal shell is formed from a flat blank by means of conical stretch-expanding at first stage and subsequent hemi-ellipsoidal stretch-expanding at second stage was experimentally investigated using blanks of 1100 commercially pure aluminum sheet. Experimental results showed that the occurrence condition of unfavorable deformation modes, such as rupture and rising, depended much on the condition of conical shell height at first stage; by selecting suitable condition of the height, the hemi-ellipsoidal shell could be formed from the aluminum blank.
    Download PDF (1125K)
  • Kiyotaka MATSUURA, Tatsuya OHMI, Masayuki KUDOH, Takashi KAKUHASHI, To ...
    1997 Volume 47 Issue 8 Pages 446-451
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    An intermetallic compound, molybdenum alumino-silicide, MoAlxSi2−x, is produced from a mixture of molybdenum, aluminum and silicon powders by using a pseudo-hot-isostatic-pressing (PHIP) process and a reactive sintering method. The mechanical properties at room temperature and oxidation behavior at 773 K and 1500 K are investigated. The increase in the PHIP pressure leads to a remarkable increase in density and hardness of the alumino-silicide. The increase in aluminum content of the alumino-silicide leads to a slight increase in density, but it does not affect the hardness. The increase in aluminum content of the alumino-silicide dramatically improves its oxidation resistance.
    Download PDF (709K)
  • Takeshi ITAGAKI, Ken TOHMA
    1997 Volume 47 Issue 8 Pages 452-457
    Published: 1997
    Released on J-STAGE: March 30, 2007
    JOURNAL FREE ACCESS
    The effect of iron content and cooling rate after brazing heat treatment on the electrochemical property and the corrosion behavior of Al–0.1 mass%Sn–Fe alloys were investigated. Pitting potential abruptly became noble at the critical iron content which decreased with the decrease of cooling rate. Tin is preferentially precipitated around Al–Fe intermetalic compounds. As the pitting of matrix initiated at the precipitates, the corrosion behavior depended on distribution of them. As the corrosion of the Al–0.1 mass%Sn–0.5 mass%Fe alloy with slower cooled after brazing heat treatment was a sort of uniform type consisting of a great many small pits, application of the alloy as a pitting corrosion resistant one can be expected.
    Download PDF (1318K)
RESEARCH NOTE
feedback
Top