Influence of Different Mixing Processes on Tensile Properties of Graphene-Nanoplatelet-Reinforced Oxide-Dispersion-Strengthened Steel Composites

In order to improve the strength, toughness and thermal conductivity of ODS steel, graphene was introduced as a reinforcement and the mixing process of powders was optimized in this work. Graphene nanoplatelets reinforced oxide dispersion strengthened steels (abbreviated as GNPs/ODS steels) composite powders were fabricated via general mechanical mixing, wet milling and dry ball milling with different parameters, respectively. The mixed powders were consolidated by Spark Plasma Sintering. The influence of different mixing processes on morphologies and structures of GNPs in mixed powder as well as tensile properties and thermal conductivity of sintered bulk GNPs/ODS steels composites were studied via x-ray diffraction, scanning electron microscopy, Raman spectroscopy, transmission electron microscopy and tensile testing machine, hot-wire method, respectively. The results show that, dry ball milling with suitable parameters can make GNPs homogeneously dispersed into the ODS steels matrix. Although the ball milling process may destroy the structure of GNPs, the sintered ODS steel exhibit the best performance, the tensile strength and thermal conductivity of bulk GNPs/ODS steels composites at RT are about 1250 MPa and 10.88 W/(m K), respectively, which increased by 37 and 22% as compared to the ODS steel without GNPs.