Micro- and macrostructural factors in DRA fracture resistance

Fracture resistance continues to be a critical, heavily researched property for discontinuously reinforced aluminum (DRA) materials because of its importance in many of the structural applications for which these materials are candidates. Over the last ten years, significant progress has been made in understanding and improving the fracture resistance ofD RA materials, largely through the control of microstructural features by judicious alloy and reinforcement selection coupled with process modification and control. This article reviews recent progress in microstructural understanding and describes directions being pursued for further improvement, especially in particle-reinforced systems. In addition, methods to improve fracture resistance that are more macrostructural in nature are being developed. These involve the combination of reinforced and unreinforced regions on a macroscale in planar and axisymmetric geometries in order to capitalize on extrinsic toughening mechanisms.