The Study On Preparation And Properties Of AlMgB₁₄ And It's Composites

Due to the higher hardness,excellent wear resistance,low coefficient of friction,high temperature stability,low density and self-lubrication ability,AlMgB14 has drawn much attention.However,AlMgB14 is brittle and its fracture toughness is 3.0-4.1 MPam1/2.So it cannot be used for machining of metal before toughening and strengthening.In this study,AlMgB14 have been synthesized by Mechanical Alloying(MA)and hot pressing sintering process.The AlMgB 14 matrix composites including AlMgB14-Ni3Al,AlMgB14-SiC,AlMgB14-70wt.%TiB2-Ni3Al were also synthesized.The microstructure and mechanical properties of AlMgB14 and AlMgB 14 matrix composites were examined.Studies show that the average hardness of AlMgB14 is 28.42 GPa,the average density is about 2.695g/cm3 and the fracture toughness is 2.92MPam.By adding a certain amount of Ni3Al in AlMgB14,the AlMgB14-Ni3Al composite material has been synthesized.The hardness and fracture toughness of this composite will decreased with the increasing of the content of Ni3Al.The reason for this phenomenon is that Al can react with Ni and then generate NiAl,which will greatly influence the hardness and fracture toughness of the composite material.AlMgB14-SiC composite material can be prepared by adding SiC whiskers in AlMgB14 The hardness and the fracture toughness will decrease gradually with the increase of SiC's content.That is mainly caused by the effect of reducing of the density of composite material.When AlMgB14-TiB2-Ni3Al composites was sintered at 1450 ?,relative density and hardness would rise gradually with the increase of Ni3Al's content.While after sintering at 1600 ?,relative density and hardness would decrease with the increase of Ni3Al.