Research on clarication of fatigue mechanism in metal matrix composites and evaluation method for its mechanical characteristics

Research Project

Project/Area Number	05650084
Research Category	Grant-in-Aid for General Scientific Research (C)
Allocation Type	Single-year Grants
Research Field	Materials/Mechanics of materials
Research Institution	KYUSHU UNIVERSITY
Principal Investigator	NOGUCHI Hiroshi Kyushu University Faculty of Engineering, Dept.of mechanical science and engineering Associate Professor., 工学部, 助教授 (80164680)
Co-Investigator(Kenkyū-buntansha)	AONO Yuuta The same as the head investigator, Research Associate, 工学部, 助手 (70264075) ODA Yasuji The same as the head investigator, Research Associate, 工学部, 助手 (20091340) NISITANI Hironobu The same as the head investigator, Professor, 工学部, 教授 (20037708)
Project Period (FY)	1993 – 1994
Project Status	Completed (Fiscal Year 1994)
Budget Amount *help	¥1,900,000 (Direct Cost: ¥1,900,000) Fiscal Year 1994: ¥900,000 (Direct Cost: ¥900,000) Fiscal Year 1993: ¥1,000,000 (Direct Cost: ¥1,000,000)
Keywords	Metal Matrix Composites / SiC Whisker / Aluminum Alloy / Fatigue Strength / Fatigue Crack Initiation / Fatigue Crack Propagation / アルミニウ合金 / 金属基複合材料 / ウィスカ / 金属疲労 / 複合材料 / 切欠き
Research Abstract	In this research, rotating-bending and push-pull fatigue tests of the SiC whisker reinforced 6061-T6,2024-T4 and 7057-6T aluminum alloy made by powder metallurgy were carried out to investigate the fatigue mechanism of plain and notched specimens at room temperature. The fatigue mechanisms in three materials were clarified through successive surface observations using the plastic replica method. Obtained results are as follows. (1) Fatigue strength of all MMC increase and are about as high as the steel. (2) The fatigue life is consumed in the fatigue propagation life of small crack by 100mum. (3) All MMC has a notch sensitivity, and the fatigue limit with a blunt notch has a large statistical factor. (4) It is indicated from (3) andf (4) that the fatigue life of all MMC has a large scatter. (5) A simple method for predictiction of statistical fatigue life is important. (6) There is an optimum volume fraction of SiC whisker for each mechanical property, and it is dependent on the characteristics of matrix.