Ceramic compounds undergoing martensitic transformation and methods for producing them, and highly-tough composite materials

摘要

The present invention provides ceramic compounds having high hardness, high strength and high toughness and which are stable even at high temperatures, and composite materials comprising them. Thus, the invention provides ceramic compounds which undergo martensitic transformation and which are represented by a rational formula, Ln1-xSixAlO3+0.5x, where Ln represents at least one selected from Sc, Y, La, Ce, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and YB, and x = 0.01 to 0.3, and composite materials comprising the compounds. For example, the compounds are produced by substituting a part of LnO1.5 in LnAlO3-type compounds with SiO2.