Improvement of tensile ductility in high-purity alumina due to magnesia addition

Abstract

High-temperature plastic flow of high-purity A1 2O 3 and MgO-doped A1 2O 3 has been examined in a temperature range 1300 ∼ 1450°C. High-purity A1 2O 3 with an initial grain size of about 0.9 μm is characterized by large strain-hardening rate and small tensile ductility up to 20%. The addition of 0.1 wt% MgO into A1 2O 3 results in a decrease of strain-hardening rate and improves tensile ductility. The tensile elongation up to 70% is obtained in MgO-doped A1 2O 3. The difference in plastic flow behavior between pure and MgO-doped A1 2O 3 is caused by the difference in grain growth during high-temperature deformation between the two materials. The grain growth inhibition caused by the MgO addition is very important to improve the tensile ductility. The tensile ductility of MgO-doped A1 2O 3 is slightly but further improved in a temperature-increasing test. The role of grain size on tensile ductility is discussed in this paper.