Abstract

A laser optoacoustic method for quantitative assessment of the volumetric porosity of cast dispersion-strengthened metal-matrix composite materials has been proposed and experimentally implemented. The method is based on a statistical analysis of the distribution of amplitudes of backscattered broadband pulses of longitudinal acoustic waves in the tested materials. Laser excitation and piezoelectric recording of ultrasound is implemented with one-way access to the test object using a special laser-ultrasonic transducer. Silumin-based composites reinforced with silicon carbide microparticles in various volume concentrations (0.033–0.135) and composites obtained by reaction injection moulding based on aluminum reinforced with intermetallic \({\text{A}}{{{\text{l}}}_{3}}{\text{Ti}}\) (volume concentration 0.04–0.115) have been studied. For both types of composites, the distribution of amplitudes of backscattered ultrasonic signals is approximated by a Gaussian distribution function applicable for a large number of statistically independent quantities. The empirically obtained dependence of the half-width of this distribution on the volumetric porosity of composites of two different types is approximated by the same linear function regardless of the manufacturing technology, as well as of the type, size, and concentration of strengthening particles.

中文翻译：

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激光光声法定量估计铸造分散增强金属基复合材料中的孔隙率

摘要

提出了一种激光光声方法，用于定量评估铸件弥散强化的金属基复合材料的体积孔隙率。该方法基于对测试材料中纵向声波的反向散射宽带脉冲幅度分布的统计分析。激光激励和超声压电记录是通过使用特殊的激光超声换能器单向访问测试对象来实现的。各种体积浓度（0.033–0.135）的碳化硅微粒增强的Silumin基复合材料，以及金属间化合物\（{\ text {A}} {{{\ text {l}}} _ {3}} {\ text {Ti}} \）（体积浓度为0.04-0.115）已被研究。对于两种类型的复合材料，后向散射超声信号的振幅分布都可通过适用于大量统计独立量的高斯分布函数来近似。根据经验获得的这种分布的半峰宽度对两种不同类型复合材料的体积孔隙率的依赖性可以通过相同的线性函数来近似，而与制造技术，增强颗粒的类型，尺寸和浓度无关。