Al_2O_3/(W,Ti)C纳米复合陶瓷材料的力学性能与强韧化机理

Toughening and strengthening mechanisms of the mechanical properties of Al_2O_3/(W,Ti) C nanocomposite

采用纳米和亚微米级的α-Al2O3,以及微米级的(W,Ti)C粉体为原料,制备了Al2O3/(W,Ti)C纳米复合陶瓷材料.在基体Al2O3含有体积分数为11%的纳米Al2O3时复合材料的抗弯强度和断裂韧性达到最优,其抗弯强度、断裂韧性和硬度分别为840 MPa,6.55 MPa.m1/2和20.1 GPa.TEM实验表明,纳米颗粒的加入明显抑止了基体晶粒的长大,形成了典型的骨架结构,材料的断裂方式为沿晶断裂和穿晶断裂的混合.内晶型和晶间型第二相颗粒产生的残余应力场、断裂模式的改变和晶粒细化强化促进了复合材料抗弯强度和断裂韧性的提高.

Al2O3/（W, Ti）C ceramic nanocomposites were fabricated from nanocrystalline α- Al2O3, micro-crystalline α-Al2O3 and （W, Ti）C. The flexural strength and fracture toughness can be remarkably increased by adding nano Al2O3 （ 11% ） particles into Al2O3 matrix. The flexural strength, fracture toughness and hardness are respectively 840 MPa, 6.55 MPa· m^1/2 and 20.1 GPa. TEM experiments indicate that low contents of nano-particles could refine matrix grains, and the microstrueture of the material is a homogenous skeleton structure. The fracture characteristics are mixed by inter-granular fracture and trans-granular fracture. Strengthening and toughening mechanisms are interpreted due to intra-granular and inter-granular grain synergistic residual stress, changes of fracture manner and an increase of the fracture toughening.