Non-destructive Investigation of AISi7Mg/SiC70p MMCs by means of Acoustic Scanning Microscopy, X-Ray and Neutron Diffraction

摘要

Particulate silicon carbide reinforced aluminium matrix composites (Al-SiC) have a high potential for advanced engineering materials beeing developed for use in traction, automotive, aviation and space applications. Especially high volume composites with up to 70 vol.% reinforcement of silicon carbide particles in a cast AlSi metal matrix (AlSi7Mg/SiC70p) show most interesting characteristics for application in high power electronics (IGBTs). To characterize such MMCs respectively reasons for failure, different non-destructive material investigations were carried out among them Acoustic Scanning Microscopy, X-Ray and Neutron Diffraction. Acoustic Scanning Microscopy delivers information about lateral density differences respectively material inhomogeneities in- tegrated over sample thickness. Diffraction methods are used for a non-destructive evaluation of absolute and phase specific residual stresses, whereas X-Ray Diffraction provides near surface information (several tens of micrometers). High Energy Synchrotron and Neutron Diffraction on the contrary provide bulk information of several millimeters up to several centimeters. Important for the understanding of the deformation behaviour and dimensional stability is the understanding of the residual stress state and inhomogeneities in the composite and its change under operating conditions respectively under dynamic thermal load.