TEM study of a hot-pressed Al2O3-NbC composite material

Abstract

Alumina-based composites have been developed in order to improve the mechanical properties of the monolithic matrix and to replace the WC-Co material for cutting tool applications. Al2O3 reinforced with refractory carbides improves hardness, fracture toughness and wear resistance to values suitable for metalworking applications. Al2O3-NbC composites were uniaxially hot-pressed at 1650 °C in an inert atmosphere and their mechanical properties and microstructures were analyzed. Sintered density, average grain size, microhardness and fracture toughness measurements and microstructural features were evaluated. Results have shown that the mechanical properties of alumina-NbC are comparable to other carbide systems. Microstructural analysis has shown that the niobium carbide particles are mainly located at the grain boundaries of alumina grains, which is an evidence of the "pinning effect", produced by NbC particles

Mechanical properties of nanomaterials: A review

“…However, larger NbC particles may act as a defect in the structure, causing a small reduction in strength. Figure 6 shows that the addition of NbC does not effectively inhibit grain growth as compared with earlier studies that used micro-alumina [43][44][45].…”

Caracterização de compósitos homogêneos e heterogêneos (materiais com gradiente funcional) a base de Al>i<>sub<2>/sub<>/i<O>sub<3>/sub<-NbC para aplicações como de ferramentas de corte

“…Durante o processamento, a presença do NbC no processamento, induz o tamanho de grão da Al O diminuir, elevando sua dureza e tenacidade, porém também dificulta a densificação do material que é muito importante para obter-se boa resistência mecânica (ACCHAR; SEGADÃES, 2005;SEGADÃES, 2009;RUMBAO;BRESSIANI, 2003). Segundo Acchar e Segadães (2009), o limite de benefício das propriedades mecânicas, como dureza e tenacidade à indentação do NbC em matriz de Al O é de 30% em peso.…”