Interfacial microstructure and mechanical property of the discontinuous short tungsten fiber-reinforced tungsten matrix composites.

For tungsten fiber-reinforced tungsten matrix (W f /W) composites, the interface between W matrix and W fiber has a dominant effect on the mechanical properties. In this study, the interfacial microstructure in the W f /W composites with or without Y 2 O 3 coating deposited on W fiber is investigated. The crystal structure of the Y 2 O 3 coating composed of nano-sized columnar grains on the W fibers is cubic. And the crystal structure of Y 2 O 3 coating changes to be face centered cubic after sintering in the W f /W composites. Two kinds of interfaces, including the interface between W matrix and Y 2 O 3 coating, the interface between W fiber and Y 2 O 3 coating, are present in the W f /W composites. Different orientation relationships are observed in these two kinds of interface. The stable orientation relationship with 111 Y 2 O 3 // 0 1 ¯ 1 W have the lowest interfacial energy. The Y 2 O 3 interface is essential for improving the toughening behavior of W f /W composites and impeding the abnormal grain growth on the surface of W fiber sintering at low temperature. The recrystallization nucleus is developed by the bonding between W powder and W fiber during sintering, and then grow fast into W fiber. The apparent activation energy of abnormal grain growth of W fibers is about 242.7 KJ/mol sintering at temperature between 1500 and 1800 °C. The abnormal large grains usually show intergranular brittle fracture and make the W fiber be brittle. • The interfacial microstructure in the W f /W composites with or without Y 2 O 3 coating is investigated. • The crystal structure of Y 2 O 3 coating changes from cubic to face centered cubic after sintering. • The orientation relationship between W and Y 2 O 3 was determined. • The Y 2 O 3 interface can impede abnormal grain growth on the surface of W fibers. • The apparent activation energy of abnormal grain growth is about 242.7 KJ/mol. [ABSTRACT FROM AUTHOR]