Critical Evaluation of Hot Forging Experiments: Case Study in Alumina

A new loading dilatometer was successfully developed and applied for hot forging experiments, assisted by two high-resolution laser beams and providing accurate determination of radial and axial strains. The application of various uniaxial loads linearly increased both radial and axial strain rates of cylindrical specimens if compared at constant density. Microstructural evolution during hot forging was followed with high-resolution scanning electron microscopy and quantitative analysis of pore size and orientation. Uniaxial loads led to elongated pores oriented in the direction of the applied load. This anisotropic microstructure exhibited an increased densification rate perpendicular to the loading axis, if free sintering was characterized after load removal. The imprinted anisotropy faded out during free sintering.

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