深过冷Cu-Ni-Fe三元合金自定向快速凝固

利用熔融玻璃净化结合循环过热，在２５～３０４Ｋ过冷度范围，分析了Ｃｕ－３９％Ｎｉ－６％Ｆｅ（ｗｔ％）三元合金凝固过程过冷组织的演化规律。确定了负温度梯度下实现自定向凝固的过冷度条件：下限为能够抑制快速凝固过程中形成的枝晶熟化的最低过冷度，上限为快速凝固过程中枝晶不发生准球状化转变的最高过冷度；就研究的合金而言，过冷度范围为１１０～１８０Ｋ。在定向凝固的过冷度范围内，无需人为控制固液界面前沿的温度梯度，而且，以点触发试样端部，可以获得单晶

Auto-Directional Solidification of Undercooled Cu-Ni-Fe Ternary Alloy

In the undercooling range of 25 304K, the micro structure evolution patterns of undercooled Cu 39%Ni 6?(wt%) ternary alloy during solidification are investigated with glass fluxing technique combined with cycling process of superheating and cooling. The undercooling condition of forming auto directional solidification is determined. Thus, the low undercooling limit is that the dendrite remelting processing must be restrained and the upper undercooling limit is the highest undercooling degrees under which the even quasi spherical grains can not be converted. As a result, the undercooling range is 110 180K for the alloy investigated. Also, the results indicate that it is not necessary to control over the temperature gradient of the undercooled liquid by human beings within the directional solidification undercooling range; and that even single crystals can be obtained by point trigging at the end of the samples.