V. Wessels

The detrimental effect of flux-induced boron alloying in Pd–Si–Cu bulk metallic glasses

We report on advanced insights into the fluxing of Pd–Si–Cu bulk metallic glasses. Flux-induced boron alloying and trapping of oxides are found to be associated with the employed boron oxide fluxing agent, and both influence the attainable glass-forming ability (GFA) in opposite ways. Incorporated boron strongly deteriorates the GFA due to a rising liquidus temperature, while the oxygen reduction improves it. Thus, proper fine-tuning of the fluxing time and overheating characteristics leads to an enhancement of GFA. In the current case, the critical diameter of Pd77.5Si16.5Cu6 bulk metallic glasses can be increased to 15 mm, as compared to 3 mm in the unfluxed case. Based on these results, we illustrate that the development of further fluxing agents is crucial for enhancement of the key properties of bulk metallic glasses.

Surface structuring of zirconium-based bulk metallic glasses using ultrashort laser pulses

A technique for structuring the surface of a bulk metallic glass (BMG) via scanning with a beam of laser pulses in the pico- and femtosecond time regime is presented. Specimens were characterized by various techniques to analyze the effects of ultrashort laser pulses on the amorphous matrix. Broadly varying surface structures, with roughness parameters in the range of Ra = 0:066 to 0:329 μm, measured using white light interferometry (WIM) and optical 3D microscopy, were produced. These techniques could be useful for fabricating biomedical implants from BMGs. As proof of principle, a patterned grid, designed for evaluating bone cell response to different surface structures, are produced.