微細中空ガラス球/Al-12%Si合金複合材料の引張強さに及ぼす基地金属と中空ガラス殻壁の有効断面積率の影響

抄録

A low density composite (Shirasu Balloons Aluminum Composites: SBAC) of volcano glass micro-balloons (Shirasu Balloons: SB) and an aluminum alloy (Al-12%Si) was investigated in terms of tensile strength. SBAC fractures abruptly at a critical tensile stress, that is a typical brittle material. The fractured surface propagates through the equatorial section of SB and the constricted parts of matrix metal where SB is in contact with together. The effective area fractions of metal and SB wall (SG) sections in the fractured surface are respectively A_M=0.363-0.282 V_SB and A_SG=(1.28+0.556 V_SB) h/R, where h and R are the wall thickness and the mean radius of SB, and V_SB is the volume fraction of SB in SBAC. The tensile strength of SBAC is proportional to the summation of A_M and A_SG since SB wall has Young's modulus nearly equal to that of the aluminum alloy. The sphericity of SB changes the stress concentration around the cavitation in SB and affects the tensile strength of SBAC.