The Group has a park of 5 dilatometers (2 horizontal ones and 3 vertical ones), 2 thermo-mechanical simulators, one quenching device and a lamp oven for the synchrotron beamline.
The dilatometers allow to follow the metallurgical evolutions during a thermal treatment by dilatation measurements, dilatation coefficients and electric resistivity. The speed heating and cooling are including between 0.001°C/s and 300°C/s in a range of temperature from -200°C and 1500°C. These features depend on the type of heating (resistive, radiation, inductive) and on sample volume.
Thermo-mechanicals simulators allow to do a link between thermals, metallurgicals and mechanicals phenomenon. The mechanical testing allow to manage experiments at a constant dilatation rate, for a steady strain or loading, and to follow simultaneously the dilatation, strength and electrical resistivity evolutions at high temperature. And well, the quenching machine allows to measure the impact of a thermal gradient on the phase transformations kinetics during a fast heating.
The quenching device allows the measurement of the influence of a thermal gradient on the kinetics of phase transformations during rapid cooling.
To develop the variety of thermo-mechanical characterizations, the Unit will acquire a hot tensile/compressive machine, in the frame of the metallurgy project to obtain behaviour laws under cyclic mechanical loads or for levels of strain that are near to forging (compression of the order of 100%).
To follow the microstructural evolution of metal alloys in real-time, the "Microstructures and stresses" Unit of the Institut Jean Lamour is often brought to use high energy X-ray diffraction on the synchrotron beamlines (ESRF, HASYLAB).
With the aim of better controlling thermal treatments applied to bulk samples (length 15 to 30 mm, diameter 3 to 6 mm), a new apparatus was specially developed within the Unit.
This original device has allowed the acquisition of the Debye-Scherrer rings during an imposed thermal treatment and the simultaneous recording of the electrical resistivity. During these events, rotation of the sample was controlled, allowing the statistics of counting to be increased, or the tensor of internal stresses to be accessed.
Furthermore, an environmental chamber was conceived to considerably limit sample oxidation.
This device was used successfully for the first time on the ESRF ID15B beamline in December 2014.
Principle of synchrotron function:
Lamp oven in place to measure the ID15B beamline:
Lamp oven during experiments on the ID15B line:
Principle of the measurements: the use of a synchrotron source to obtain a high energy beam (87keV) and thus analyze the samples by real time transmission with a 2 dimensional detector allows an acquisition time per image of 0.1 s. The 2D images thus obtained were integrated to be exploited by different methods, including the Rietveld method to obtain phase fractions and cell parameters for each phase.
Evolution of the volume fractions during cooling of a composite with a metallic matrix (steel-TiC) from 900ºC to room temperature. The volume fractions were determined by Rietveld analysis of the diffractograms (Lilian Vautrot's thesis project).
Evolution of cell parameters of phases present in a composite with a metallic matrix (steel-TiC) upon cooling from 900ºC to room temperature (Lilian Vautrot's thesis project).