Mg₂Si粒子強化マグネシウム合金基複合材料の疲労挙動

抄録

This paper describes the fatigue behaviour of Mg₂Si-particulate reinforced magnesium alloy composites. Rotating bending fatigue tests have been performed using smooth specimens of two materials, Mg₂Si/AZ 31-H and Mg₂Si/AZ 31-L, extruded at high and low billet temperatures, respectively. Fatigue strength was evaluated and compared with a conventional extruded AZ 31 alloy, and fracture mechanisms were discussed. Fatigue strength was strongly affected by billet temperature during the extrusion process, where Mg₂Si/AZ 31-L exhibited significantly higher fatigue strength than Mg₂Si/AZ 23-H. When compared with the extruded AZ 31 alloy, Mg₂Si/AZ 31-L also showed slightly higher fatigue strength. In Mg₂Si/AZ 31-L, fatigue cracks initiated in the matrix microstructure near particles, while in Mg₂Si/AZ 31-H, generated at the interface between the matrix and particles, and subsequent small cracks grew faster in Mg₂Si/AZ 31-H than in Mg₂Si/AZ 31-L, which were responsible for the observed billet temperature dependence of fatigue strength.