先进材料疑固实验室 Dendrite arm spacing Laboratory of Advanced Materials Solidification ⊕ The primary arm spacing is an important characteristic of columnar dendrites and has a marked effect on the mechanical properties.It is assumed that the cell or the dendrite envelope,representing the mean cross-section of the trunk and branches,can be described approximately by an ellipse.The radius of curvature of the ellipse R is given by: b2 R- a ATo b is the semi-axis,is proportional △T toλ1，the primary arm spacing, a G where the proportionality constant Te depends on the geometrical arrangement of the dendrites. Co b=0.58λ1 上游文通大学 SHANGHAI JIAO TONG UNIVERSITYDendrite arm spacing The primary arm spacing is an important characteristic of columnar dendrites and has a marked effect on the mechanical properties. It is assumed that the cell or the dendrite envelope, representing the mean cross-section of the trunk and branches, can be described approximately by an ellipse. The radius of curvature of the ellipse R is given by: b is the semi-axis, is proportional to λ1, the primary arm spacing, where the proportionality constant depends on the geometrical arrangement of the dendrites