Лазерный оптико-акустический метод количественной оценки пористости литых дисперсно-упрочненных металломатричных композиционных материалов

Abstract

A laser optoacoustic method for quantitative porosity assessment of cast particulate reinforced metalmatrix composite materials is proposed and experimentally realized. The method is based on statistical analysis of the amplitude distribution of backscattered broadband pulses of longitudinal ultrasonic waves in the studied materials. Laser excitation and piezoelectric detection of ultrasound are realized by one-side access to a tested object using a special laser-ultrasonic transducer. Stir cast siluminmatrix composites reinforced with the SiC micro particles (volume fractions 0.033–0.135) and in-situ reactive cast aluminummatrix composites reinforced with the Al3Ti intermetallic particles (volume fractions 0.04–0.115). For both types of composites, the amplitude distribution of backscattered ultrasonic signals is approximated by the Gaussian distribution function applicable for statistics of large number of statistically independent variables. The derived empirical dependence of the half-width of this distribution on the volume porosity of two different types of composites is approximated by one and the same linear function independently of the fabrication technique, as well as on the type, size, and volume fraction of reinforcing particles.