SiCp颗粒增强铝基复合材料非共线非线性响应试验观察

采用粉末冶金方法制备的碳化硅颗粒增强铝基复合材料(SiCp/Al)受加工过程工艺影响较易出现SiCp颗粒分布不均等缺陷。传统的金相法及声速扫描法检测该缺陷存在破坏试样及定位困难且灵敏度不高等问题；基于谐波的穿透式共线非线性无损检测方法检测灵敏度高，但易受到其他非线性试验来源的干扰。为解决这一问题，利用基于波束混叠的非共线非线性超声检测方法，观察SiCp/Al的非共线非线性响应，探讨使用该方法检测粉末铝基复合材料非均匀性缺陷的可行性；建立非共线非线性超声检测试验系统，发现LY12铝合金及SiCp/Al试样内部的波型转换与波束混叠现象；利用非共线技术的空间可达、波型转换及频率方向可控等性质，成功剔除了非线性的试验来源，从试验上证明该方法能够观测试样内部的非线性，具备检测SiCp/Al试样均匀性的潜力。试验方法与结果为进一步研究非共线混叠波与粉末铝基复合材料均匀性的相关关系及扫查方法奠定基础。

Experimental Observation of Nonlinear Response of SiCp Aluminum-matrix Composites Using Non-collinear Technique

SiCp reinforced aluminium-matrix composites manufactured by using powder metallurgy method typically have inhomogeneity defects. To evaluate the inhomogeneity condition, conventional metallographic method would destroy the sample, and ultrasonic scanning method based on wave velocity has difficulties on defect locating and testing sensitivities. Collinear nonlinear ultrasonic method like harmonic generation is an optional solution, but the inhomogeneity induced nonlinearities are small and often masked under other sources of nonlinearities. To solve the aforementioned problems, a non-collinear nonlinear ultrasonic testing technique based on wave beam mixing is proposed to observe the nonlinearities of SiCp/Al samples, and the feasibility of the method to detect inhomogeneity defect is discussed. A non-collinear nonlinear ultrasonic system is developed to observe the wave beam mixing properties of LY12 Al alloy and SiCp/Al samples and the waveform mode transformation is obtained in the experiments, as well. The experimental nonlinearities have been successfully removed by spatial, mode, frequency and direction selection properties of the technique making the experimental method more robust. The experimental results show that the non-collinear technique based on wave beam mixing has the potential to be used to detect inhomogeneity defect of SiCp reinforced aluminium-matrix composites and the conclusion can be used in future scanning detection.