The Properties And Characterization Of AlMgB₁₄-TiB₂Composites Prepared By Field-activated And Pressure-assisted Sintering

The super hard material AlMgB14has attracted wide attention for its high hardness, chemical inertness, excellent wear resistance, cheap raw materials and low friction coefficient in recent years. Recent studies show that AlMgB14-TiB2composites have a great number of special performances such as wear resistance, thermal conductivity and strong toughness. The highest micro hardness can be up to48GPa. AlMgB14-TiB2composites were mainly used in industries of metal cutting, military project, forestry, mining, petroleum, agriculture and such kind of special machines, for its ability to stand a wide range of temperature.The AlMgB14and its composites have been synthesized by the way of the Mechanical Alloying (MA) and FAPAS process in this paper. The microstructure and component of synthesized AlMgB14-TiB2composites were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). We have been investigated the preparation technology, synthetic principle, mechanical properties and densification of AlMgB14composites; Still, the characterization of the fracture toughness of AlMgB14and its composites are done with the micro-hardness indentation method while we use the abrasive wear experiment to measure the abrasive resistance. The results show that with the Al powder, Mg powder and B powder, the AlMgB14bulk materials is prepared as follows:sintering temperature1500℃, heating rate100℃/min, axial pressure60MPa and the heat preservation8-10min. After annealing, boron powder can effectively control the generation of oxide. Adding ceramic cube in the graphite mould could improve the efficiency of sintering and obtain high density current. The highest hardness of AlMgB14prepared under these conditions would reach to27.2GPa while the average density is about2.631g/cm3and the fracture toughness is3MPam1/2. The AlMgB14-TiB2composites, TiB2additive and AlMgB14matrix have good compatibility. The interface is tightly bonded and do not generate new phases. By observing the micro structure, we can find that adding TiB2can effectively improve the micro hardness and fracture toughness. The micro hardness of AlMgB14-30%TiB2is31.5GPa and the fracture toughness could reach to3.65MPa-m1/2, which is20%higher than AlMgB14. The room temperature friction and wear test show that adding TiB2into AlMgB14could significantly reduce the wear rate and improve the wear resistance. Under the same load, the abrasion loss of AlMgB14-TiB2composites show a trend of decrease and the wear abrasion resistance increases along with TiB2increasing. Scratch width of AlMgB14-TiB2composites also increase along with the added pressure.