Determination of dendrite coherency point characteristics in Al-Si-Mg alloy

ABSTRACT

Dendrite coherency or dendrite impingement is an important factor for determining solidification microstructure and casting defects of alloys. In this research, the effect of various cooling rates and Al-5Ti-1B grain refiner contents on the dendrite coherency point (DCP) characteristics of an Al-Si-Mg alloy designated as A357 has been studied. The results showed that both mentioned parameters have a significant influence on DCP of this alloy. Increasing the cooling rate from 0.15 to 1.0 °C/s and the grain refiner content from 0.0 to 3 wt. % increased the solid fraction in where dendrite coherency occurs. Moreover, enhancement of the cooling rate and grain refiner could increase the difference between the liquidus and coherency temperatures (T_N–T_DCP), about 27 and 26 °C, respectively. The dendrite coherency time decreased by increasing the cooling rate and increased by increasing the grain refiner content.

KEYWORDS:

• Al-Si-Mg alloy
• dendrite coherency point
• thermal analysis
• grain refinement
• cooling rate

Disclosure statement

No potential conflict of interest was reported by the authors.