Thermo-mechanical testing of tantalum carbides using a Lorentz-force, non-contact technique

A thermo-mechanical testing apparatus has been constructed where an electrical current provides resistive heating and, in the presence of a magnetic field, a Lorentz force for the application of a load on a test bar specimen. The electromagnetic Helmholtz coil can be used to independently control the magnetic flux, or load, while adjusting the specimen current for resistive heating of the specimen. The coils and specimen were encased in a stainless steel chamber that controlled the testing environment. The apparatus successfully deformed test bars of γ-TaC at 2600 °C and 3100 °C for 30 min. The temperature and deflection measurements were simulated using a finite element model. During the thermo-mechanical testing, the equiaxed grains grew isotropic with the intrinsic porosity, observed in pre-tested grain boundaries, providing microstructural markers of the grains initial size, shape and location in the microstructure.