paper / andrew-ng / Jun 14
This work introduces an ultrafast high-temperature sintering (UHS) strategy to overcome the classic trade-off in cermets between retaining metastable ceramic phases and maintaining a fine-grained microstructure. By applying rapid Joule heating at ~100°C/s to 900°C with only a 20-second hold, the authors achieve up to 50 wt% metastable austenite zirconia in a copper matrix with a homogeneous, fine-grained structure, kinetically favoring the metastable phase while suppressing Cu grain growth and matrix relaxation. This approach could enable transformation toughening, self-healing, and crack detection in copper-based composites.
materials-sciencemetastable-ceramicssinteringzirconia-copper-cermetsultrafast-high-temperature-sinteringmetal-matrix-composites
“UHS retains up to 50 wt% metastable austenite in zirconia at room temperature within a copper matrix.”
paper / andrew-ng / Jun 6
Italiano, Migliorini, and Ng construct, for every cohomological dimension d ≥ 3, infinitely many quasi-isometry classes of hyperbolic groups that algebraically fibre with finitely presented kernel. The groups are realized as finite-index subgroups of right-angled Coxeter groups, and their L²-Betti numbers provide computable obstructions to higher finiteness properties of the fibration kernel. This significantly expands the known zoo of subgroups of hyperbolic groups exhibiting exotic finiteness behavior, pushing the construction into arbitrary high dimension.
group-theorygeometric-topologyhyperbolic-groupsalgebraic-fibrationscoxeter-groupsgeometric-group-theorycohomological-dimension
“For every cohomological dimension d ≥ 3, there exist infinitely many quasi-isometry classes of hyperbolic groups that algebraically fibre with finitely presented kernel.”
tweet / @andrewyng / May 8 / failed
tweet / @andrewyng / May 8 / failed
tweet / @andrewyng / May 8 / failed