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Dual‐grained (Ti, W)C–Ni cermets by two‐step carbonization: Hot isotropic press sintering of NiTiW alloys and colloidal graphite
Author(s) -
Xiong Huiwen,
Wen Yu,
Li Zhiyou,
Zhou Kechao
Publication year - 2019
Publication title -
journal of the american ceramic society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.9
H-Index - 196
eISSN - 1551-2916
pISSN - 0002-7820
DOI - 10.1111/jace.16261
Subject(s) - cermet , materials science , sintering , carbonization , graphite , microstructure , carbon fibers , metallurgy , composite material , chemical engineering , ceramic , scanning electron microscope , composite number , engineering
Abstract Reactive sintering of crushed metals and carbon is advantageous for preparing toughened complete solid‐solution cermets (CSCs). Here, dual‐grained (Ti 0.6 , W 0.4 )C–18Ni cermets were prepared using a two‐step carbonization method. High‐energy milling of Ni–Ti–W–C (Ni(Ti 0.6 , W 0.4 ) 4 C) mixture afforded NiTiW solid solution, which was then transformed into Ni 6 W 6 C by heating at 1250°C. Twinned (Ti, W)C platelets were formed by the carbonization of Ni 2 W 4 C during liquid sintering. W atoms that accumulated in the (111) planes of TiC promoted the {111} twin formation, leading to sandwich‐type (Ti, W)C platelets. Dense (Ti 0.6 , W 0.4 )C–18Ni cermets were obtained by hot isostatic press sintering in Ar with satisfactory Hv of 12.8 ± 0.2 GPa, high strength of 1960 ± 84 MPa and toughness of 15.80 ± 0.6 MPa·m 1/2 . A higher sintering temperature or graphite content accelerated the carbonization, resulting in coarser platelets with decreased aspect ratio. This study provides a new approach to modify the microstructure of CSCs and a method for preparing dual‐grained cermets.