Grants and Contributions:

Grant or Award spanning more than one fiscal year. (2017-2018 to 2022-2023)

The current impetus in aluminum alloy development for automotive applications has been mainly due to government legislation requiring automotive manufactures to significantly improve fuel efficiency of new vehicles. Aluminum alloys are ~65% lighter than ferrous alloys, and therefore have a great potential to be used in many automotive applications. Another focus of lightweighting in the industry is to develop advanced, low-displacement, high power density engines. This trend frequently demands increased operating temperatures and pressures for powertrain components, therefore making many currently used alloys unfit for their respective applications due to, for example, insufficient strength. Both trends lead to demand for higher-performing alloys and the need to develop and test new alloying systems.

Many aluminum alloys are being developed based on Al-Si, Al-Cu, as well as Al-Ce systems, aiming improved wear resistance, strength, castability, and lower cost. Mechanical properties of these alloys, however, largely depend on resulting microstructure, which may depend on micro-alloying additions and process variables. Variations in microstructure characteristics lead to ambiguity of results of comparative fitness-for-service testing of different alloys.

In this Discovery program, we will undertake an innovative approach to the development of higher performing alloys with mechanical properties tailored to a specific application. As these properties are dependent upon alloy composition and intermetallic phases present in the microstructure, to study kinetics of phase evolution this project will include thermodynamic calculations of the solidification and cooling using the FactSage software, experimental thermal analysis (DSC), and in-situ neutron diffraction (ND) for real time monitoring of phase evolution. FactSage and DSC analysis may not provide sufficient information due to the known limits of either pure-theoretical equilibrium or Scheil approximation of the solidification mode in calculations, while the heat transformations detected in DSC may relate to simultaneous evolution of several phases. Such shortcomings can be addressed with application of in-situ ND coupled with Rietveld analysis. This novel approach will allow for studying specific effect that microalloying additions may have on microstructure evolution, allowing real time monitoring of evolution of individual solid phases, a capability only available with ND analysis. The samples used in this study will further be analyzed using “more traditional” optical and SEM microscopy and XRD.

This research will provide HQPs hands-on and fundamental knowledge in the fields of manufacturing and materials science, and provide a solid foundation for advanced lightweight alloys development for the most challenging applications, such as cylinder blocks and engine heads for the next generation engines.