Ultrahigh transverse rupture strength in tungsten-based nanocomposites with minimal lattice misfit and dual microstructure

D Chakravarty and N Laxman and R Jayasree and RB Mane and S Mathiazhagan and PVV Srinivas and R Das and M Nagini and M Eizadjou and L Venkatesh and N Ravi and DR Mahapatra and R Vijay and SP Ringer and CS Tiwary, INTERNATIONAL JOURNAL OF REFRACTORY METALS & HARD MATERIALS, 95, 105454 (2021).

DOI: 10.1016/j.ijrmhm.2020.105454

New-generation structural materials with superior properties are a constant demand in applications involving extreme environments. Here, we demonstrate the fabrication of a high-strength, high-dense W-TaC-Ta2O5 nanocomposite for such applications on a large scale by a simple, cost- effective, scalable, bottom-up powder metallurgy approach using plasma sintering. The first clear microstructural evidence of the scavenging effect of carbide particles in the W-MC composites (M = Ta, Zr, Hf, Ti) is demonstrated through atom probe studies. Localized plastic deformation and the unique stress-induced amorphization in tungsten are observed due to dislocation activities, and these phenomena are corroborated by molecular dynamics (MD) simulations. Optimized composition and processing conditions yield high Vickers hardness -540 HV10 and super-high transverse rupture strength (TRS) similar to 1650 MPa, in upscaled components of 100 mm diameter. The enhanced mechanical properties are attributed to the cumulative effect of the grain boundary strengthening and dispersion strengthening from the refined tungsten grains and the second phase intragranular nanocrystalline particles, respectively, the coherent particle-matrix interfaces, the low oxygen- segregation at grain boundaries and the 'dual nano crystalline- amorphous' microstructure present in the matrix.

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