INTERFACE REACTION OF BORON CARBIDE IN ALUMINUM MATRIX COMPOSITES AND ITS CONTROL

摘要

Aluminum matrix composites containing reinforcing particles of B_4C have been used in highperformance applications such as neutron shielding components and aircraft and aerospace structures. B_4C is a desirable reinforcement because of its special capability to capture neutrons, its lightweight, and its superior stiffness and strength. However, further use of B_4C particlereinforced composite material is limited due to its complicated manufacturing and high cost. One of the major challenges is controlling the interface reaction between B_4C and Al-matrix which is detrimental to castability and material properties. The present paper describes work conducted to better understand the interface reaction during the liquid metal mixing process and the resulting cast structure. The instability of B_4C in liquid aluminum and its reaction products were investigated using thermodynamic calculation, optical metallography and scanning electron microscopy. A novel method is presented for controlling the interfacial reaction by forming an in-situ barrier layer using a Ti addition in molten aluminum.