Densification Control in Hot Pressing of Metallic Glass Powders
Densification Control in Hot Pressing of Metallic Glass Powders
复制标题
金属玻璃粉末热压过程中的致密化控制
DOI：
10.2497/jjspm.55.709
复制
发表时间：
2008
期刊：
影响因子：
--
通讯作者：
A. Kawasaki
中科院分区：
文献类型：
--
作者：
R. Watanabe;N. Yodoshi;H. Kato;A. Kawasaki
本文导出了金属玻璃粉末热压过程中粘性流动控制致密化的方程，提出了金属玻璃粉末完全致密化的判据和控制孔隙率的途径。动力学方程推导的基础上Arzt的热压理论，其中的致密化是由收缩的Bolonoi细胞的随机致密堆积的球形颗粒。粘性流动的本构方程是从迄今为止提出的蠕变速率方程设置速率指数为1。由于在致密化后期形成的三个晶粒边缘的变形的假设约束被考虑作为动力学方程中的压力项的修改。相对密度表示为热压时间和粘度与压力之比的函数。结果表明，金属玻璃粉末完全致密化所需的时间只取决于粘度/压力比。完全致密化的判据表示为时间-粘度/压力比平面上的一条直线，该直线将区域划分为完全致密区和多孔区。金属玻璃粉末压坯的孔隙率控制也被证明是本理论的另一个实际应用。结果进行了讨论的基础上报告的数据。
The equations for the densification control by viscous flow in the hot pressing of metallic glass powders are derived and a criterion for the full densification thereof and an approach for the porosity control are proposed. The kinetic equations are derived on the basis of Arzt's hot pressing theory; in which the densification is modeled by the contraction of the Bolonoi cell of the random dense packing of spherical particles. The constitutive equation for the viscous flow is obtained from the hitherto proposed creep rate equation setting the rate exponent to be unity. The hypothetical constraint for the deformation due to the three grain edges formed in the later stage of densification is taken into account as a modification of the pressure term in the kinetic equations. The relative density is expressed as functions of hot pressing time and the ratio of the viscosity and the pressure. It is shown that the time required for full densification of metallic glass powders depends only on the viscosity/pressure ratio. The criterion for the full densification is expressed as a straight line on the time-viscosity/pressure ratio plane, which divides the area into full-dense and porous areas. The porosity control of the metallic glass powder compacts is also demonstrated as another practical application of the present theory. The results are discussed on the basis of the reported data.