Elevated temperature embrittlement in mechanically alloyed Al-Fe-V-Si alloy extrusion

摘要

Tensile behavior of mechanically alloyed Al-8.5Fe-1.3V-1.7Si alloy extrusions, with various grain sizes ranging from0.1 to 0.6 μm, were examined within the temperature rangebetween 25℃ and 250℃ . It was found that both tensilestrength and ductility gradually decreased with increasingtemperature and/or decreasing strain rate. The SEM fractographicexamination showed that MA/PM Al-Fe-V-Si alloy extrusionsfailed by dimpled rupture, regardless of test conditions. The sizeand depth of dimples, however, differed considerably withdifferent testing temperatures and strain rates. TEM micrographsof deformed specimens showed that the formation of dislocationstructures within the grain was extremely limited at each testtemperatures, and was further restricted at elevated temperatures.The present observations suggest that the enhanced dynamicrecovery is responsible for the nil work hardening and plasticinstabilities between growing voids at elevated temperatures,leading to a reduced tensile ductility.