New materials for powder injection molding - High entropy alloys and ceramic matrix composites

Abstract

Probably the most decisive benefit of Powder Injection Molding (PIM) is the wide range of materials. As a logical consequence current R+D activities target on the adaptation of new metal and ceramic materials. Modern high-performance materials like e.g. Ni-based super alloys are widely applied. For further progress development of so-called High-Entropy-Alloys (HEA) characterized by a minimum of five elements with all of nearly the same content, i.e. an equiatomar composition, started. These alloys represent a quite new field in metallurgy expected to offer attractive properties like high thermal strength and/or increased ductility. For initial trials a Co20Cr20Fe20Mn20Ni20 alloy was used. Injection and sintering procedures were developed and the resulting densities were examined. Processing of Ceramic Matrix Composites by PIM represents a considerable challenge. Development of a process chain for the ceramic injection molding of Al2O3 short fiber CMC has been performed. Fiber content varied between 10 to 50 vol.% whereas for binder a well-examined system from KIT was chosen. As expected the fiber content showed a major effect on the rheological properties and fiber orientation depended strongly on the apparent shear profile. Both parameters affected the sintering behavior as well.