High-pressure work hardening of alumina. Issue 14 (15th July 2021)

• Record Type: Journal Article
• Authors: He, Deng; Liu, Fangming; Guan, Shixue; He, Duanwei
• Is Part Of: Ceramics international. Volume 47:Issue 14(2021)
• Page Start: 19989
• Page End: 19994
• Publication Date: 2021-07-15
• Subjects: Alumina -- Vickers hardness -- High-pressure and high-temperature sintering -- Work hardening; Ceramics -- Periodicals; Céramique industrielle -- Périodiques; Ceramics; Periodicals; Electronic journals; 666
• DOI: 10.1016/j.ceramint.2021.04.009
• Languages: English
• ISSNs: 0272-8842

Abstract

Abstract: We report a method for strengthening microcrystalline alumina compaction by work hardening under conditions of high pressure and temperature, in which the hardness significantly improved. Micro-sized spherical alumina powders were treated without additives under 5.5 GPa–14 GPa and 600 °C–1200 °C. A polycrystalline sample sintered at 12 GPa and 900 °C yielded a Vickers hardness of 30.0 GPa, which was 1.5 times that of single-crystal alumina and the highest value reported to date for alumina. By analysing the density, hardness, and microstructure of the sintered samples, the results demonstrated that under ultra-high pressure and below the recrystallisation temperature of alumina, plastic deformation of the grains produced many substructures such as stacking faults and lattice distortions showing obvious work hardening effects. Combined with well-bonded crystalline and amorphous grain boundaries, the hardness of the samples was unexpectedly enhanced.