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材料科学技术学报 2008
Effect of Different Rare-Earth on Microstructure and Properties of α-Sialon CeramicsKeywords: Rare-earth,Microstructure,Mechanical properties Abstract: Densified Yb-,Y-,Dy-,Sm- and Nd-α-Sialon ceramics were prepared by two-step hot sintering.The variation of microstructure and properties with different rare-earth was investigated.The ceramics doped with smaller cations (Yb3 ,Y3 and Dy3 ) are fully composed of α-Siaion,while in the larger cations (Sm3 and Nd3 ) doped ceramics also exist a few intergranular phase M' (Re2Si3-xAlxO3 xN4-x) in triple-point pockets.With increasing the radius of the rare-earth cations,the elongated α-Sialon grains form instead of the equiaxed grains in Yb-α-Sialon,and the aspect ratio of grains increases.All the ceramics possess high hardness,and the value of 21 GPa is achieved for Yb- and Y-α-Sialon.With increasing the ionic size of rare-earth,the hardness decreases slightly but the toughness tends to increase.Nd-α-Sialon possesses the highest toughness with the value of 5.4 MPa·ml/2.
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