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Abstract

This research investigated the effects of high-intensity ultrasound on the combustion synthesis of TiC particles in Al-Ti-C system. The process involved that high-intensity ultrasound was applied on the surface of a compacted Al-Ti-C pellet directly through a Nb probe during the thermal explosion reaction. By comparing with the sample without ultrasonic treatment, it was found that the thermal explosion reaction for synthesizing TiC phase could take place thoroughly in the ultrasonically treated sample. During the process of synthesizing TiC phase, the dissolution of solid graphite particles into the Al-Ti melt, as well as the nucleation and growth of TiC particles could be promoted effectively due to the effects of ultrasound, leading to an enhancement of the formation of TiC particles. Ultrasound assisted combustion synthesis as a simple and effective approach was proposed for synthesizing materials in this research.

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While aluminum-silicon (Al-Si) alloys are one of the most versatile aluminum alloys, iron is considered one of the most harmful elements in Al-Si diecasting application. Its presence leads to the precipitation of many AlFeSi intermetallic phases and unacceptable mechanical properties, such as reduction in ductility. Thus controlling the fraction and morphology of the AlFeSi phase, especially the β-AlFeSi phase is an important way to improve the ductility of Al-Si die casting alloys. In this article, Ca/Mn, Ca/Sr and Sr/Mn elements were added into A380 alloys to study the effect of combined element addition on the morphology change of the AlFeSi phase. Sr and Ca addition can impair the modication effect and introduce sludge. Mn and Ca, Mn and Sr can result in a microstructure consisting of fcc α-Al, modi ed eutectic Si, α-AlFeSi Chinese script phases and a re ned platelet β-phase. However, use of high cooling rates can better re ne the morphology of the AlFeSi phase and lead to a better alloy product.