Ti 元素对B4C/Al复合材料力学性能的改善作用研究

Improvement on mechanical property of B4C/Al composites by addition of Ti through interfacial reaction

摘要:

B₄C/Al复合材料是目前最理想的中子吸收材料,广泛用于乏燃料储存。本文利用液态搅拌法制备B₄C/Al复合材料,通过添加Ti元素,探讨了界面反应对材料的界面结构和力学性能的影响。研究发现,Ti元素通过参与界面反应,改变了界面结构,在B₄C颗粒表面形成了紧密结合的纳米TiB₂界面层；Ti的添加消除了界面微裂纹、微孔、分离等缺陷。随着界面反应程度的加强,材料强度提高,尤其反应脱落的纳米TiB₂颗粒作为原位第二强化相进一步增强基体。B₄C/Al复合材料断裂过程表现为韧窝延性断裂；TiB₂界面层增强了B₄C颗粒与基体的结合,断裂行为从B₄C-Al界面脱落转变为B₄C颗粒断裂；但过渡的界面反应会形成微韧窝,引起材料延伸率下降。

Abstract:

A fine bonded interface is essential for the property of metal matrix composites. In this paper, an innovative method to strengthen boron carbide reinforced aluminum composites (B₄C/Al composites) was studied by liquid stirring technology. The effect of interfacial reaction on the microstructure and mechanical behavior of B₄C/Al composites was revealed by addition of Ti. Through B₄C-Al melt interfacial reaction, Ti element strongly enriched at the interface. A dense and continuous nanoscale layer of TiB₂ was formed on the surface of B₄C particles. Interfacial modification was achieved by interfacial reaction. Due to the formation of TiB₂ layer with good wettability and bonding, interfacial defects were eliminated. Increasing the degree of reaction, such as Ti content and reaction time, the strength of B₄C/Al composites was gradually improved. Severe interfacial reaction introduced lots of nano-scale TiB₂crystals into the matrix, which as in situ second reinforcement also improved the strength of B₄C/Al composites. Fracture behavior of B₄C/Al composites with different interfacial modification was discussed at last.