Infiltration kinetics, microstructure and mechanical properties of B4C-MgSi composite fabricated by melt infiltration
ZOU Zhihuan1, ZENG Fanhao1,2, LIU Ji’an1, LI Yi1, GU Yi3, ZHANG Fuqin1,2
1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China; 2. The National Key Laboratory of Science and Technology onHigh-Strength Lightweight Structural Materials, Changsha 410083, China; 3. School of Materials Science and Engineering, Central South University, Changsha 410083, China
Abstract：B4C-MgSi composites were prepared by vacuum perpetration with infiltrating porous B4C substrates at 1 000 ℃ with a Mg-Si eutectic alloy. The theoretical calculation shows that at the temperature of 1 000 ℃, the infiltration depth of molten Mg in porous B4C increases with increasing time, and the penetration rate is faster first and then tends to be stable. The infiltration depth can reach more than 2.2 cm after 60 min for Mg, while MgSi alloy, under the same conditions, has a greater depth. The phase composition was tested by XRD. The microstructures of B4C substrates and B4C-MgSi composites were analyzed by scanning electron microscope (SEM). The mechanical properties were also studied. The results show that the porosity of B4C-MgSi composites have many connected pores, and the density is more than 98% after the melting. The composites displays high rockwell hardness (71.3±3.3 HRA), good bending strength (285.81±11.2 MPa) and high fracture toughness (5.27±0.53 MPa·m1/2). A mixed fracture morphology of B4C-MgSi composite is indicated. It is different from the brittle fracture of B4C substrates.
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2018, Vol. 23 
