W-Ni-Fe系机械合金化过程中的相变及热力学和动力学研究

Studies on Thermodynamic and Kinetic and Phase Evolution of W-Ni-Fe Powder during Mechanical Alloying

W,Ni,Fe粉末按照91.16W6.56Ni2.28Fe的成分配比进行机械合金化(MA)。用XRD确定物相,用TEM(JEM-2000CX型)观察微观形貌和显微结构。并对机械合金化粉末的物相、颗粒尺寸、晶格畸变作了分析讨论。MA可以使W-Ni-Fe系形成纳米晶超饱和固溶体和非晶。参照Miedema半经验理论模型,计算了该合金系的相变驱动力,热力学分析指出该合金系不存在发生非晶化反应的化学驱动力。应用固态反应模型解释了MA过程非晶形成的热力学可能性,在MA过程中,非晶的形成并不绝对要求体系ΔHmix<<0和DB>>

91.16W6.56M2.281Fe tungsten heavy alloy from the elemental powders of W, Ni and Fe was mechanically alloyed(MA). Phase was defined by XRD. Microstructure was observed by TEM (JEM-2000 type). Phase evaluation, grain size and lattice distortion of these powders were determined and discussed. And nano-crystalline supersaturated solid solutions and amorphous were prepared by MA. A thermodynamic model was developed based on Miedema semi-experimental theory to calculate the driving force for phase evolution. The thermodynamic analysis showed that there is no chemical driving force to form amorphous alloys. The model of multilayer amorphization during MA was applied to illustrate the feasibility of amorphization of powder with neither DeltaH(mix) much less than 0 nor D-B much greater than D-A.