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Aluminum alloys containing cerium have excellent castability and retain a substantial fraction of their room temperature strength at temperatures of 200°C and above. High temperature strength is maintained through a thermodynamically trapped, high surface energy intermetallic. Dynamic load partitioning between the aluminum and the intermetallic increases mechanical response. Complex castings have been produced in both permanent mold and sand castings. This versatile alloy system, using an abundant and inexpensive co-product of rare earth mining, is suitable for parts that need to maintain good properties when exposed to temperatures between 200 and 315°C.

In the early 1980's, some promising research and development efforts focused on powder metallurgy revealed that aluminum alloys containing 4 wt% cerium exhibit high temperature mechanical properties exceeding those of the best commercial aluminum casting alloys currently in production. Cerium oxide is an abundant rare earth oxide that is often discarded during the refining of more valuable rare earths such as Nd and Dy. Therefore, the economics are compelling for cerium as an alloy additive. In this paper, we report select results obtained during an investigation of the castability of aluminum-cerium alloys and determine compositional modifications that may be required to ensure the compatibility of the alloy with near net shape casting methods such as advanced sand casting, die casting, permanent mold casting and squeeze casting. Al-Ce alloys were cast in binary composition of 6-16 wt% Ce. Commercially pure aluminum ingots were melted and held at approximately 785°C.

Cylinder liners exert a major influence on engine performance, reliability, durability and maintenance. Various combinations of nonmetallic reinforcements and coatings have been used to improve the tribological performance of sleeves or surfaces used in compressors and internal combustion engines in four stroke, two stroke and rotary configurations. In this paper we report the use of a hybrid composite containing silicon carbide and graphite in an aluminum alloy matrix to improve the performance of various small engines and compressors. Material properties of the base material, as well as comparative dynamometer testing, are presented.

Aluminum Metal Matrix Composites (AMMCs) have similar but not identical casting characteristics of the base aluminum alloy. The differences in viscosity and the presence of ceramic particles cause unique casting issues, many of which can be addressed in the casting design process. The properties of AMMCs are different than both aluminum and cast iron in many ways. Those differences create design opportunities that are sometimes overlooked. This paper will attempt to develop a framework for the design issues surrounding AMMC castings.

It has been shown that fly ash can be incorporated in aluminum alloy matrix using stir casting and pressure infiltration techniques; additions of fly ash have been shown to decrease the density and coefficient of expansion of aluminum and increase its wear resistance. This paper summarizes the work in progress at University of Wisconsin-Milwaukee and Eck Industries, Inc. on incorporating fly ash in aluminum castings to decrease the cost and weight of selected industrial components. Aluminum alloy A356 - fly ash and 319-fly ash composite ingots and selected parts were successfully cast in sand and permanent molds using conventional foundry techniques from large scale heats (400 pounds). The sand and permanent mold castings including differential carriers, intake manifolds, brake drums and outdoor equipment castings show adequate castability of the melts containing fly ash particles.

Metal matrix composite alloys combine the attributes of metals and ceramic reinforcements to provide materials engineered with low density and high specific mechanical properties. Most components do not require the high performance capability of aluminum MMCs throughout their entirety. Reinforcement of only the high stress regions of a component will reduce manufacturing costs. This is referred to as selective reinforcement. Data that may be used to facilitate this approach to component design and manufacture is presented. The predicted effect of the interface between reinforced and un-reinforced regions is also discussed.

Preliminary work was conducted in the casting of magnesium using the lost foam casting process. The lost foam or expendable pattern casting (EPC) process is capable of making extremely complicated part shapes at acceptable soundness levels and with low manufacturing costs. Standard test shapes were used to determine the ability of the magnesium to fill the mold and to assess the types of defects encountered. This paper will briefly explain how this project evolved including the developmental strategies formed, the products selected, the casting trials performed, and the casting results.