Methods

Sample preparation

Several methods are employed for the rapid quenching of metallic alloys:

Splat-Quenching: The liquid sample is quenched between two copper pistons.
Melt-spinning: This method, which is also commercially very common, produces narrow ribbons by quenching the melt on a rotating copper wheel.
Mold-Casting: Solidification in a cooled copper mold yields bulk samples.
Samples for investigation by ultra sound or neutron diffraction are inductively melted in a quartz tube and quenched in water.
Vapor deposition of glass forming alloys onto a cold substrate under UHV-conditions yields amorphous thin films.

Sample characterization

To characterize structure and properties of the samples we use differential scanning calorimetry (DSC), energy dispersive X-ray spectroscopy (EDX), wide angle X-ray scattering (WAXS), scanning electron microscopy(SEM), atomic force microscopy (AFM), etc.

Mechanical spectroscopy

For low frequencies (0.1-50Hz,) and a temperature range of -100°C to 1000°C, we use a dynamic mechanical analyzer (DMA) to apply static and dynamic forces on the sample.

For the kilo hertz range (about 5.4 kHz), the double paddle oscillator (DPO) is a very sensitive tool. Operated at its resonance frequency, it allows for the analysis of mechanical properties of thin films.

For low temperatures (RT -2K) a pulse echo ultra sound measurement unit (USO) is used, which can detect very small changes in the elastic moduli for a given frequency in the MHz range.

Investigation of undercooled melts

The thermo physical properties of undercooled melts are quantitatively analyzed by observing the oscillation of a droplet during a parabola flight. For this purpose a contact free electro magnetic processing unit in zero gravity is employed in collaboration with DLR Köln/Bonn. The images of the deformation during oscillation are digitalized and the contours are fitted polynomially. Thus, thermal expansion can be measured with an accuracy of up to 10-6 K-1.