ABSTRACT
The Diesel engine, introduced by Rudolph Diesel in 1892, achieves a higher combustion ratio and fuel efficiency, has lower CO2 emissions per mile than the gasoline engine and is considered to be one of the most viable environmentally friendly technologies for vehicles. “Clean Diesel” using lower sulfur content fuel has become available since 2006. Currently, the Diesel engine and cylinder head are mostly cast iron to withstand the high compression pressures and temperatures of Diesel operation. Further weight reduction (40%–55%) via aluminum substitution in the Diesel engine would result in substantial fuel economy and increased environmental benefits. Current aluminum alloys cannot meet the requirements of the Diesel engine and a new research topic has emerged in aluminum materials technology to address these requirements. The main issue with aluminum alloys is the low resistance to thermal fatigue that results from the constrained expansion and contraction of the material in the interval regions leading to compressive creep deformation at 300°C during engine heat-up and to tensile deformation around 150°C during engine cooldown. This article discusses the performance requirements and the design principles for aluminum alloys for Diesel engine applications. Efforts on the modification of A356 and A319 alloys via Cu, Mg, Ni, Cr, V, Zr, Ti, and Mn addition are reviewed. Recent studies on Mn/Mo addition are presented and the related principles are introduced in designing high volume fraction, thermally stable, and uniform nanoscale dispersoids using solutes with opposite partitioning coefficients in aluminum.
