Reactive synthesis and ultrafast sintering of refractory compositionally complex alloy-carbide composites
May 6, 2025
Researchers from the University of California San Diego, La Jolla, California, USA, have released a paper in Scripta Materialia focused on the reactive synthesis and ultrafast sintering of refractory compositionally complex alloy-carbide composites.
NbMoTaW – a refractory compositionally complex alloy (RCCA) with a well-dispersed compositionally complex carbide (CCC) reinforcing secondary phase – is made through high-energy ball milling (HEBM) and ultrafast high-temperature sintering (UHS). The study successfully demonstrated the use of ultra-fast sintering of RCCA-CCC composites to deliver high relative densities (approx. 92-95%) in around seventy seconds.
The researchers used stearic acid PCA as a carbon source to form a controllable fraction of well-dispersed (i.e. harder) CCC phase(s) in the metallic RCCA matrix.
The high heating and cooling rates during ultrafast sintering also enabled the formation of the favourable P3¯m1 subcarbide CCC phase (Nb0.37Mo0.11Ta0.39W0.13)2C. A thermodynamic model was proposed to explain the Nb and Ta enrichments in (Nb0.37Mo0.11Ta0.39W0.13)2C from more negative carbide formation energies for Nb2C and Ta2C. An additional rock-salt monocarbide CCC was found only in RCCA-20CCC (with the highest 1 wt% PCA addition). The well-dispersed CCC phase reduced the grain size and improved the hardness.
‘Reactive synthesis and ultrafast sintering of refractory compositionally complex alloy-carbide composites’ is available here.
