Abstract

Stirring based liquid metal processing is the widely explored process by researchers for the production of metal matrix composites (MMCs). The dispersion of reinforcement particles is the major challenge in the process. The stirring process parameters govern the dispersion of reinforcement particles in MMCs. The important stirring process parameters are stirring speed, stirrer geometry, stirrer position, and stirring time. In the literature, research works are reported, where the effect of such parameters on the dispersion of particles was investigated either by analyzing flow field using computational methods (assuming constant fluid properties) or by sectioning the casted samples. In cast condition, the dispersion of particles is also influenced by the solidification phenomena. The aim of the present work is to investigate the significance and the effect of stirrer geometry, stirrer position and stirring speed on the dispersion of reinforcement particles inside melting crucible, during the stirring. Aluminium alloy LM25 was used as the matrix material and silicon carbide (SiC) particles having mean size 37.58 microns (d₅₀ value) were used as the reinforcement phases. Samples of the composite slurry during the stirring process were dragged using a quartz tube at three levels inside crucible and microstructure analysis was carried out. Number density (ND) and inter particle distance were evaluated for parameter combinations. The uniform dispersion of SiC particles was observed at 45° stirrer blade angle, 400 rpm stirring speed and 40 mm stirrer position. And, significance order of individual parameter was observed as stirring speed < stirrer position < stirrer blade angle.

Graphic Abstract

摘要

基于搅拌的液态金属加工是研究人员广泛研究的用于生产金属基复合材料（MMC）的过程。增强颗粒的分散是该过程中的主要挑战。搅拌工艺参数控制着增强颗粒在MMC中的分散。重要的搅拌过程参数是搅拌速度，搅拌器几何形状，搅拌器位置和搅拌时间。在文献中，报道了研究工作，其中通过使用计算方法（假定流体特性不变）分析流场或对铸件进行切片来研究这些参数对颗粒分散的影响。在铸造条件下，颗粒的分散也受凝固现象的影响。本工作的目的是研究搅拌过程中搅拌器几何形状，搅拌器位置和搅拌速度对增强颗粒在熔融坩埚内分散的意义和影响。铝合金LM25被用作基质材料，平均尺寸为37.58微米的碳化硅（SiC）颗粒₅₀值）用作增强阶段。使用石英管将搅拌过程中的复合浆液样品在坩埚内的三个位置拖动，并进行微观结构分析。评估了参数组合的数密度（ND）和粒子间距离。在45°搅拌器叶片角度，400 rpm搅拌速度和40 mm搅拌器位置观察到SiC颗粒均匀分散。并且，观察到各个参数的显着性顺序为搅拌速度＜搅拌器位置＜搅拌器叶片角度。

图形摘要