TiB_2粒子强化富镍NiAl的初步研究

应用快速凝固技术和放热弥散(XD)方法研制了Ni-20.2wt％Al-0.9wt％TiB_2~-复合材料,其中TiB_2~-粒子的平均尺寸为0.2μm,富镍的NiAl基体平均晶粒尺寸随凝固冷速不同为1.4～4.3μm。TiB_2~-粒子主要分布于基体晶界上,由于TiB_2~-粒子和基体晶粒尺寸均很小,所以TiB_2~-粒子的分布仍然很均匀,并与基体有很强的结合。弥散分布的TiB_2~-粒子与位错产生了强烈的相互作用,在TiB_2~-粒子之间形成了位错网络,因而对基体产生了有效的强化作用。在晶粒尺寸和铝含量相近时,NiAl-TiB_2~-的室温显微硬度约为NiAl的1.5倍。这一复合材料还需进一步研究其高温性能与界面稳定性。

PRELIMINARY RESEARCH ON REINFORCING NICKEL-RICH NiAI BY TiB_2~- PARTICLES

Ni-20.2wt％-0.9wt％TiB_2 composit was developed using a combination of rapid solidification technology and XD processing. The average size of TiB_2~- particles was about 0.2μm and that of the grains of nickel-rich NiAl matrix were 1.4-4.3μm with different cooling rates during solidification. TiB_2~- particles distributed mainly on the grain boundaries of the matrix. Since the sizes of grains of nickel-rich NiAl and TiB_2~- particles were very small, the distribution of the TiB_2~- Particles still was very homogeneous and the bouding between particles and matrix was very strong. TiB_2~- particles with dispersive distribution reacted strongly with the dislocations and the dislocation networks among the particles were formed so TiB_2~- particles played effectively a strengthening role for the nickl-rich NiAl. The microhardness at room temperature of NiAl-TiB_2 was about 1.5 times as larger as that of NiAl when grain sizes and aluminium contents of them wew nearly the same. The further research on mechanical properties and interface stability at elevated temperatre of the composite would be necessary.