Evolution of the microstructure in carbon nanotube reinforced Nickel matrix composites processed by high-pressure torsion

摘要

Carbon nanotube (CNT)-reinforced nickel matrix composites were processed using high-pressure torsion (HPT) at room temperature (RT). Different CNT weight fractions were used in order to study the behavior of the composites in the "as sintered" and the "as deformed" conditions and to determine the effect of the amounts of CNT added on the different processing methods. The samples were analyzed by means of Vickers microhardness and electron microscopy. According to the results, increasing the CNT content in the "as sintered" condition increases the agglomerate size but decreases only slightly the grain size. Regarding the "as deformed" condition it showed little to negligible effect in further refining the microstructure. By means of HPT the hardness was increased up to 800%. It was concluded that the microstructure could be further improved in terms of grain size and agglomerate size and distribution by means of HPT.