Cu-Zn-Sn体系富Sn区液相限的研究

近些年来,无铅低熔点填料日渐引起人们的兴趣,且将得到广泛的应用。Cu-Zn-Sn合金正是无铅低熔点填料的一种基本合金。该体系相图虽有一些报道,但他们的研究只涉及富铜区(>50Wt％)的液相限和等温截面(500℃)。我们颇感兴趣的富Sn区的液相限,尚未见文献报道,因此测定该体系富Sn区的液相限是必要的。关于Cu-Zn-Sn体系的三个相关二元体系,已有文献报道,也较成熟。对于Cu-Zn体系,富Zn区600℃以下存在两个转熔反应,其转熔点分别为Q(～88Wt％Zn,598℃),W(97.5-98.5Wt％Zn,424℃);Cu-Sn体系富Sn区有一个转熔反应,其转熔点

AN INVESTIGATION ON LIQUIDUS OF Sn-RICH CORNER OF Cu-Zn-Sn SYSTEM

The liquidus of the Sn-rich range in the phase diagram of Cu-Zn-Sn system has been investigated by means of thermal analysis and X-ray diffraction method. It was found that there are five surfaces corresponding to the primary crystalliza- tion of Sn, η-Cu_6Sn_5, ε-Cu_3Sn, ε-CuZn_(~6), and η-Zn respectively and three invariant points: E, the ternary eutectic point, (90.8 Wt.%Sn, 0.2wt. %Cu; 190 ℃) and two ternary peritectic points P_1(91.3Wt.%Sn, 5.8Wt.%Cu; 358 ℃) and P_2(~0.2 Wt. %Cu, 96.3Wt. %Sn; 218 ℃) in the Sn-rich range. No ternary intermetallic compound was detected.