SiC Particle Detection in Liquid Aluminum via Laser Induced Breakdown Spectroscopy

Aluminum alloy castings are becoming commonplace for critical applications in the automotive and aerospace industries where materials failure is not an option. Tight control over the cleanliness of the melt (mitigation of solid particle inclusions and dissolved gases) and microstructure must be achieved. Very few techniques exist that can quantitatively measure inclusion levels in-situ. The use of laser-induced breakdown spectroscopy (LIBS) has shown promise as a technique to quantify solid particles, wanted and unwanted, in aluminum melts. SiC particles were added to pure aluminum and analyzed with LIBS, and traditional metallography. An algorithm, based on the Nalimov test, was used to differentiate between LIBS signal from the matrix and particles. Initial tests show a linear relationship between SiC concentration and LIBS signal.