Effect of Annealing on Microstructure and Mechanical Properties of AlCoCrFeMoNi High-Entropy Alloys.

The effect of annealing temperature on the microstructure, phase constituents and mechanical properties of AlCoCrFeMoNi high-entropy complex alloys has been investigated at a fixed annealing time (10 h). The 600 °C-annealing has no obvious effect on their microstructures, while the annealing at 800-1200 °C enhances the precipitation of (Al,Ni)-rich ordered BCC phase or/and (Cr,Mo)-rich σ phase, and thereby greatly affects the microstructure and mechanical properties of the alloys. All the annealed AlCoCrFeNi alloys are composed of FCC and (Al,Ni)-rich ordered BCC phases; the phase constituent of the AlCoCrFeMoNi alloy changes from FCC + BCC (600 °C) to FCC + BCC + σ (800 °C) and then to FCC + BCC (1100 °C); the phase constituents of the AlCoCrFeMoNi and AlCoCrFeMoNi alloys change from FCC + BCC + σ to FCC + BCC with the annealing temperature rising from 600 to 1200 °C; while all the annealed AlCoCrFeMoNi and AlCoCrFeMoNi alloys consist of FCC, BCC and σ phases.

Correlation of effective dispersive and polar surface energies in heterogeneous self-assembled monolayer coatings.

We show, theoretically, that the measured effective dispersive and polar surface energies of a heterogeneous surface are correlated; the correlation, however, differs whether a Cassie or an Israelachvili and Gee model is assumed. Fluorocarbon self-assembled monolayers with varying coverage were grown on oxidized (100) silicon surfaces in a vapor phase process using five different precursors. Experimentally, effective surface energy components of the fluorocarbon self-assembled monolayers were determined from measured contact angles using the Owens-Wendt-Rabel-Kaelble method.