Fabrication of Lotus Metals Consisting of Two Different Metals Using Continuous Casting Technique with Multiple Molds

点击翻译按钮获取中文摘要

Lotus-type porous metals with pores elongated in one direction are expected to be applied to light-weight structural materials of transport machineries. In this study, lotus aluminum alloys were fabricated using Al-Si, Al-Cu, Al-Si-Mg and so on by unidirectional solidification, and the morphologies of pores were investigated. The pores generated and grew in the eutectic region among several dendrite arms. The shape of pores reflected the morphologies of the surrounding dendrite arms. The size of pores was in the same order as the dendrite arm spacing. Furthermore, lotus-type porous magnesium ingots were fabricated in pressurized hydrogen atmosphere through a mold casting technique. The mold consisted of two cooling blocks placed at the bottom and one lateral side. It was found that the pores started to grow upwards and horizontally and the both directional pores merged and then shifted to the direction. Such anisotropic growth directions of pores were in good agreement with the directions of the temperature gradient predicted by two-dimensional finite differential analysis. The mechanisms were investigated for the interruption of pore growth, the collision of two pores grew from two solid-liquid interfaces, the formation of curved pores, and the pore coarsening at the bonding plane of two solid-liquid interfaces.