半固态热等静压Al/B4C复合材料液相流动行为与致密化机理

Liquid Phase Flow Behavior and Densification Mechanism of Al/B4C Composites Fabricated via Semisolid Hot Isostatic Pressing

摘要:

铝基碳化硼复合材料是一种重要的中子吸收材料。为了制备具有更高密度的铝基碳化硼材料,研究采用粉末冶金半固态热等静压方法制备了含量为30%碳化硼的铝基碳化硼材料,采用WANCE100型材料力学性能试验机和SIRION200型扫描电镜研究了复合材料的力学性能及显微形貌。结果表明：半固态热等静压工艺可制备获得接近理论密度的Al/B4C复合材料；虽然Al/B4C材料抗拉强度可提升至约300Mpa,但过高碳化硼含量也使得该材料脆性特征十分明显；研究同时采用间接的方法观察到了半固态工艺过程中生成的液相,该液相不仅可改善碳化硼颗粒与铝基体的结合性,在高温高压下液相的流动还起到填充复合材料内部空隙的作用。半固态热等静压工艺过程中产生的液相是复合材料密度和机械性能提升的主要原因。

关键词:铝基碳化硼; 半固态;液相;致密化机理

Abstract:

Aluminum matrix Boron carbide (Al/B4C) composites is an important thermal neutron shielding material. In order to prepare B4C/6061Al composite with higher density, Al/B4C composites reinforced by 30wt.% B4C particle were fabricated via hot isostatic pressing in the semi-solid temperature range of 6061Al. Microstructures, mechanical properties and densification mechanism of the composites were investigated. The results indicate that the density of Al/B4C composite is very close to the theoretical density with the usage of semisolid hot isostatic pressing. Although the tensile strength can reach up to 300 MPa, the ductility of the semisolid HIP Al/B4C composite is not good mainly because of the high content of 30wt%B4C. Aluminum liquid phase is observed indirectly which mainly formed during semisolid temperature range of 6061Al, it is helpful to improve the combination between the B4C particles and the 6061Al matrix. The increasing of density and Strength property mainly also due to the effect of aluminum liquid flows into the internal gaps under the hot isostatic pressing condition with high temperature and high pressure.

Key words:Al/B₄C composites; semisolid; liquid phase; densification mechanism.