John Kang WebMD | DMLS Amorphous Metal Processing
John Kang of the WebMD-Medical Manager Corporation looks into the current events in the development behind bringing amorphous metals to commercial production.
In a recent study conducted by SindreMetals, Inc., a North Carolina SME that was awarded a grant by the NationalScience Foundation, researchers used direct metal laser sintering (DMLS) to produce a fully (X-ray diffraction) XRD-amorphous FeCrMoCB (metal alloy) iron-based bulk metallic glass (BMG) whose thickness is more than 15 times the critical casting thickness in all dimensions, and larger than any traditionally produced Fe-based BMG recorded.
Image Source: education.mrsec.wisc.edu
This is because, says John Kang WebMD, solidification rates necessary to obtain an amorphous microstructure come with a dimensional constraint on BMGs. The maximum thickness and dimensions of BMGs achievable through traditional manufacturing is limited to 5cm to 10cm in thickness for metal alloy (ZrTiCu1NiBe) and 12mm for metal alloy FeCrMoCBEr.
To solve this problem Liquidmetal Coatings, LLC, a subsidiary of Liquidmetal Technologies Inc., produced a gas atomized powder FeCrMoCB metal alloy with a nominal particle size distribution of 20 to 80 micrometers.
Selective laser melting was performed with a fiber laser in a chamber flooded with argon gas to limit the oxygen content to avoid material contamination. The system was tested with a wide range of heat variables along with laser parameters were tested to uncover the optimum conditions for melting.
John Kang WebMD says, based on the results of the parameter search, two cylinders measuring 30mm with a diameter of 45mm were produced. This yielded an increased density from 96.5% to 97.7% In addition; restitution was estimated using a stainless steel ball drop test where the ball dropped bounced back to almost 100% of its original height compared to the 30% yielded by a ball dropped on a stainless steel surface.
In short, the correct laser treatment has the potential to drastically amplify the desirable qualities of the amorphous metal, such as durability and restitution because Laser heat treatment can reduce the stress created my heating by reducing the thermal gradient between melting and solidified material.
Currently, Liquidmorphium, a patented non-magnetic metal alloy made from zirconium, copper, aluminum, nickel and silver developed by Liquidmetal Technologies Inc., is being developed for use in small consumer electronics, timepieces, medical, and dentistry technology, and sports equipment.
Liquidmorphium is more durable and corrosion resistant than titanium has a 53 Rockwell C hardness and can bend up to 1.8% without losing its original form. Injection molding allows it to be formed into complex shapes, comparable to plastic molding and with CNC level tolerances and repeatability.
The larger and thicker alloy castings can result in a significant impact on the material’s potential applications in commercial industries today.
John Kang WebMD-Medical Manager Corporation is an early investor and chairman of LM Group Holdings Inc., the parent group of Liquidmetal Technologies Inc., and Liquidmetal Coatings LLC mentioned above. Liquidmetal Technologies Inc. developed the Liquidmorphium alloy for commercial applications while Liquidmetal Coatings LLC produced the gas atomized powder FeCrMoCB metal alloy used in the study.
To keep abreast of the latest developments in amorphous metals, visit John Kang’s Website.