NiAl(Co)-TiC粉末的机械合金化原位制备纳米复合材料

In-situ TiC Particles Reinforced Nano-composite Synthesized by Mechanical Alloying NiAl(Co)-TiC Powders

用高能球磨机分别对四种成分的Ni50 Al50 x Cox+10%(体积分数,下同)TiC(x=5,10,20)和Ni50 Al45 Co5+20%TiC粉末进行机械合金化,得到原位内生TiC弥散强化的NiAl(Co)纳米复合粉末。结果表明,球磨Ni50 Al45 Co5 10%TiC粉末过程中,爆炸反应机制生成NiAl(Co)和TiC化合物,其中NiAl(Co)化合物晶粒仅为10nm左右,TiC晶粒为35～50nm。但当TiC含量增加到20%时,其爆炸反应起始时间延后20min。同时随着Co含量增加,Ni50 Al40 Co10 10%TiC粉末的机械合金化的产物仍为NiAl(Co)和TiC,但NiAl(Co)化合物的生成机制转变为扩散反应机制。进一步增加Co含量(20%,原子分数)则导致了γ Ni(Al,Co,Ti,C)过饱和固溶体的形成,反应机制仍为互扩散反应。

The in-situ dispersed TiC reinforced NiAl(Co) matrix nano-composites were obtained after four kinds of elemental powders, i. e. Ni_(50)-Al_(50-x)-Co_x+10%(volume fraction)TiC (x=5,10,20) and Ni_(50)-Al_(45)-Co_5+20%(volume fraction) TiC were mechanically alloyed in a high-energy ball mill. In the NiAl(Co) and TiC nano-compounds, the grain size of NiAl(Co) is only about 10nm and that of TiC is 35～50nm when ball-milling Ni_(50)-Al_(45)-Co_5-10% (volume fraction)TiC powders by the reaction mechanism of the explosive reaction. It was found that the initial time of the explosive reaction was delayed 20 minutes as the volume fraction of TiC was increased to 20%. NiAl(Co) and TiC nano-compounds were obtained using mechanically alloying Ni_(50)-Al_(40)-Co_(10)-10%(volume fraction)TiC powders. However, increasing with the content of Co, the mechanism of the forming process was changed from the explosive reaction (5% Co, atom fraction) to the inter-diffusion reaction (10%Co, atom fraction). The γ-Ni(Al, Co, Ti, C) super saturation solid solution were formed during ball-milling Ni_(50)-Al_(30)-Co_(20)+10% (volume fraction)TiC with inter-diffusion reaction mechanism.