Authors:
Jazmina Navarrete-Cuadrado (1,2), Tomas Soria-Biurrun (1,2), Lorena Lozada-Cabezas (1,2), Steven Moseley (3), Patricia Alveen (4), Jose M. Sanchez-Moreno (1,2)
1- CEIT-Basque Research and Technology Alliance (BRTA), Spain.
2- Universidad de Navarra, Tecnun, Spain.
3- HILTI CORPORATION, Liechtenstein
4- EURICE – European Research and Project Office GmbH, Germany
Abstract:
WB4-B-TaB2 based materials with hardness values over 42 GPa have been obtained by glass encapsulated HIPing. Sintering of WB4-B-TaB2 powders is significantly activated by Ni additions. Porosity removal is achieved at 1100ºC-150 MPa- 1hour, that is, 250ºC below the temperature needed without nickel. However, there is strong chemical reactivity between Ni and WB4-B-TaB2 powders leading to the formation of W2B5, NiB, Ni4B3 and M2B5 phases. Since no metallic nickel remains after sintering, these ceramic composites are very brittle. Strength and toughness of WB4-B-TaB2-Ni alloys are notably improved by TiAl3 and Zr additions. Although Ni containing borides are still present in these materials, there are also Ni-rich regions free of boron after sintering, which provide a significant strengthening effect, reaching fracture strength values near 1 GPa. However, when Zr is added to the mixtures, WB4 grains are fully decomposed into a combination of mixed borides.
DOI:
https://doi.org/10.59499/EP246281649
