This study investigated the effect of aging and thermomechanical treatments on the mechanical properties of a nanocluster-strengthened ferritic steel, Fe-1.5Mn-2.5Cu-4.0Ni-1.0Al (wt pct). The effect of thermomechanical treatments on the microhardness and tensile properties were measured at room temperature and correlated with microstructural features. Cu-rich precipitates were characterized by transmission electron microscopy and were found to coarsen slowly during long-time aging. The microhardness measurements indicate a typical precipitation hardening behavior during aging at 773 K (500°C). Tensile tests showed that thermomechanical treatments can improve the mechanical strength and ductility of the nanoclusterstrengthened ferritic steel significantly compared with those without the treatments. Fractography results indicated that the high yield strength resulted from precipitation hardening makes the steel more susceptible to grain-boundary decohesion, which can be suppressed by grain refinement. Atmosphere adsorption and diffusion along grain boundaries were found to intensify brittle intergranular fracture, and this embrittlement can be avoided by vacuum heat treatment.

The thermal stability, glass-forming ability (GFA), and mechanical and electrical properties of Au-based Au x Si 17 Cu 75.5-x Ag 7.5 (x = 40 to 75.5 at. pct) metallic glasses were investigated. The glass transition temperature (T g ) and crystallization temperature (T x ) decreased with increasing Au content. The ultralow T g values below 373 K (100°C) were obtained for alloys with x = 55 to 75.5. The alloys with x = 45 to 70 exhibited a high stabilization of supercooled liquid and a high GFA, and the supercooled liquid region and critical sample diameter for glass formation were in the range of 31 K to 50 K and 2 to 5 mm, respectively. The compressive fracture strength (r c,f ), Young's modulus (E), and Vicker's hardness (H v ) of the bulk metallic glasses (BMGs) decreased with increasing Au content. A linear correlation between Au concentration and the characteristic temperature, i.e., T g and T x , and mechanical properties, i.e., r c,f , E, and H v , as well as electrical resistivity can be found in the BMGs, which will be helpful for the composition design of the desirable Au-based BMGs with tunable physical properties.