Creep of Polycrystalline MgO and MgO‐Fe2O3 Solid Solutions at High Temperatures

Publisher Website
Google Scholar
Abstract
Polycrystalline MgO and MgO‐Fe2O3 solid solutions (0.10 to 8.08 wt% Fe2O3) were fabricated to almost theoretical density by vacuum hot‐pressing. Specimens were creep‐tested in air under four‐point dead‐load conditions between 1000° and 1400°C at stresses between 50 and 550 kg/cm2. Steady‐state creep was never achieved in the experiments, which sometimes lasted more than 50 h. The strain rate vs time (t) data were described by an equation of the form =c1/(t+C2)p, which is consistent with the assumptions that creep occurs at least in part by a “viscous” mechanism and that grain growth occurs simultaneously. Doping MgO with Fe2O3 enhanced the viscous contributions to creep and inhibited the nonviscous ones. Creep rates in these specimens increased with increasing Fe2O3 additions. The occurrence of simultaneous grain growth during the high‐temperature creep of magnesiowustite (i.e. MgO‐Fe2O3 solid solutions) was used in establishing the strain rate vs grain size dependence. The results of this study are consistent with a transition between grain boundary and lattice diffusion mechanisms as the grain size increases (4 to 44 μan). The creep of polycrystalline MgO is a mixed process in that viscous and nonviscous (dislocation) contributions are present.

This publication has 24 references indexed in Scilit: