抄録
The deformation behavior of metallic hollow spheres (MHSs) at elevated temperatures is examined by numerical analysis and experiments for a unit cell model as a basis of building up a constitutive equation for the firing process of MHS compacts. Changes in terms of reductions in height, contact area and equatorial diameter in compression under a constant load are clarified for a single hollow sphere with various shell thicknesses by viscoplastic finite element (FE) analysis. Compression tests for the real unit cell, made of eight iron hollow spheres, are performed at high temperatures by using a thermomechanical analyzer (TMA) to verify the numerical calculations. The material constants are also determined, by similar compression tests, for bulk specimens made from the same iron powder as the MHS material. The compressive behavior of the iron hollow sphere structure at elevated temperatures can be described well by the FE model with a diffusional creep law.
