Yu Mei Zhou,Feng Lin Zhang,Peng Cheng Li,Kun Bai,Shang Hua Wu
AlMgB14 is a very hard and brittle material which need be modified for utilizing as cutting tool materials. In present study, TiB2 and Ni3Al were used to strengthen and toughen AlMgB14 material. The microstructure of the AlMgB14-TiB2-Ni3Al composites was analysized by scanning electron microscope (SEM) with energy dispersive X-ray spectroscopy (EDX) and an X-ray diffractometer (XRD). The hardness and fracture toughness of the AlMgB14-TiB2Ni3Al composites were also examined. The results showed that the major phases in AlMgB14-Ni3Al composites were TiB2, AlMgB14, MgAl2O4 , Ni3Al and NiAl. With the increasing of the amount of Ni3Al, more intergranular fractured features can be found in the fractured surface of the composites, the hardness and fracture toughness of the composites were both decreased comparing to the synthesised AlMgB14. The AlMgB14-TiB2-4wt.% Ni3Al composite has a hardness of 28.1 Gpa and a fracture toughness of 3.14 MPa·m1/2.
Y.M. Zhou,T. Zhang,K. Xu,F.L. Zhang,K. Bai,H.P. Huang,S.H. Wu,S.M. Luo
Owing to great hardness and low friction coefficients on steel, AlMgB 14 has several potential applications in the fields of cutting tools and wear-resistant materials. In the current work, the effect of Y 2 O 3 addition on the mechanical properties and microstructure of spark plasma sintered AlMgB 14 and AlMgB 14 -TiB 2 has been investigated. An increase in the amount of Y 2 O 3 led to an increase in the number of secondary phases including MgAl 2 O 4 and Y 2 O 3 in AlMgB 14 matrix. The addition of Y 2 O 3 led to a refinement in the grain size of AlMgB 14 and AlMgB 14 -TiB 2 ; however, simultaneously increased the porosity. With the addition of 3 wt% Y 2 O 3 , both AlMgB 14 and AlMgB 14 -TiB 2 reached the finest grain size and the highest hardness while maintaining a low porosity.
The aim of this paper was to find a new way to synthesize the hard, super-abrasive ceramic AlMgB14 from elements. The reactive sintering was by the field-activated and pressure-assisted synthesis (FAPAS) method performed at 1400°C for 7 min under a pressure of 60 MPa. The various samples produced were observed and determined by the scanning electron microscopy (SEM), the energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and the transmission electron microscopy (TEM). The results showed that the products contained AlMgB14 with a few Al2MgO4. These samples had a highest hardness of 28.9 GPa. The average density of the samples was 2.62 g/cm3, and the fracture toughness was 3.21 MPa·m0.5. Annealing boron powder in vacuum was an effective way to reduce the oxygen contamination. When Al2O3 tube was used to isolate the powders from die, the concentrated AlMgB14 was obtained at a lower temperature in a shorter time, for the electric current could flow through the powders entirely.
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