The mechanical properties of engineering materials are key for ensuring safety and reliability. However, the plastic deformation of BMGs is confined to narrow regions in shear bands, which usually result in limited ductilities and catastrophic failures at low homologous temperatures. The quasi-brittle failure and lack of tensile ductility undercut the potential applications of BMGs. In this report, we present clear tensile ductility in a Zr-based BMG via a high-pressure torsion (HPT) process. Enhanced tensile ductility and work-hardening behavior after the HPT process were investigated, focusing on the microstructure, particularly the changed free volume, which affects deformation mechanisms (i.e., initiation, propagation, and obstruction of shear bands). Our results provide insights into the basic functions of hydrostatic pressure and shear strain in the microstructure and mechanical properties of HPT-processed BMGs.

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Phase change random access memory (PCRAM) devices exhibit a steady increase in resistance in the amorphous phase upon aging and this resistance drift phenomenon directly affects the device reliability. A stress relaxation model is used here to study the effect of a device encapsulating layer material in addressing the resistance drift phenomenon in PCRAM. The resistance drift can be increased or decreased depending on the biaxial moduli of the phase change material (YPCM) and the encapsulating layer material (YELM) according to the stress relationship between them in the drift regime. The proposed model suggests that the resistance drift can be effectively reduced by selecting a proper material as an encapsulating layer. Moreover, our model explains that reducing the size of the phase change material (PCM) while fully reset and reducing the amorphous/crystalline ratio in PCM help to improve the resistance drift, and thus opens an avenue for highly reliable multilevel PCRAM applications.

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Even though bulk metallic glasses (BMGs) are generally brittle, they receive large plastic deformations of over 1000% shear strain without fracturing through the application of combined shear and hydrostatic stresses. In this study, the effects of the severe plastic deformation by high-pressure torsion (HPT) on the thermal and mechanical properties of La 62 Cu 12 Ni 12 Al 14 BMG are investigated. Crystallization is not detected during the HPT processes with 5, 15, and 30 revolutions. However, increase in glass transition temperature, crystallization temperature, fracture strength, and fracture strain, and decrease in the coefficient of thermal expansion and hardness due to the HPT process are found. These changes in the properties are attributable to the increased free volume that results from the rejuvenated structure in the HPT-processed BMG. In addition, the fracture in the HPT-processed La 62