The mechanical behavior of superconductor lamellar-like BaFe2As2 single crystals was investigated at nanoscale by instrumented indentation. The unique responses of the ab- and a(b)c-crystallographic planes were discussed based on their influence in hardness (H) and elastic modulus (E). The results allowed two main conclusions. (i) The choice of testing parameters strongly affected the scaling of mechanical properties on the lamellar surfaces. Lamellar cracking was the leading mechanism of deformation, featuring a brittle-like behavior and affecting considerably H and E. However, the plastic deformation history allowed different elastic–plastic responses on the ab-plane owing to the compaction of the material. Threshold loads for cracking depended on both loading rate and penetration velocity, pointing out to time-dependent plastic deformation mechanisms. (ii) Proper estimates were achieved for H in multiple loading tests [3.4 GPa for ab- and ∼1 GPa for a(b)c-planes], and for E under loads less than 3 mN (∼55 GPa for both planes).

Basic scientific questions and tantalizingly revolutionary applications have been intertwined throughout the 100-year history of superconductivity. Within two years of his discovery of superconductivity in 1911, H. Kamerlingh Onnes imagined high-field applications for superconducting wires, only to have his hopes dashed by limitations of upper critical field and critical current density. Over the next 98 years, a scientific tango would play out repeatedly between (1) discovering and understanding new superconductors, often with higher transition temperature values and (2) improving these materials’ upper critical field and critical current values while keeping manufacturing costs down. In this article, we take stock of where the field currently stands, with mature, developing, and recently discovered superconductors, and try to give a sense of where it may be going.

Growth experiments have been carried out to characterize the occurrence and development of porosity in Bridgman and flux grown Al-Pd-Mn icosahedral quasicrystals. The porosity level has been observed to fluctuate between values of 0.0 and 3.75 percent along the length of Bridgman single crystals implying that the development of porosity is affected by the local growth conditions. Experiments were conducted to evaluate the influence of the rate of solidification on the occurrence of porosity. Alloys were solidified with different growth rates, 1mm/hr and >10 mm/hr, using the Bridgman configuration and at different cooling rates, ranging from 0.29°C/hr to 10°C/hr, using the flux growth method. Porosity levels were analyzed via optical image analysis. These experiments indicate that porosity percentages are greatly influenced by cooling rates and crystal size.