(1. 武汉大学 物理科学与技术学院，武汉 430072；
2. 湖南金联星特种材料股份有限公司，岳阳 414005)
摘 要: 以Al、K2TiF6、KBF4和Al-20Sr(质量分数，%)中间合金为原料，利用三步加料法和热挤压工艺制备Al-5Ti-1B-10Sr复合中间合金线材(d 9.5 mm)。该线材表面光滑，无气泡、起皮、裂纹等缺陷。组织结构分析表明：金属间化合物Al4Sr相为块状，平均长度为43.2 μm，宽度为26.8 μm，其内部或边缘存在许多孔洞和细缝； Al3Ti相呈颗粒状，平均直径为14.4 μm；TiB2颗粒非常细小，平均尺寸为1.42 μm，其中95.77%为尺寸≤1.97 μm以下的颗粒。将该复合中间合金应用于Al-13Si合金的细化与变质处理后，合金基体的α(Al)晶粒得到明显细化，共晶Si相也由粗大的针状组织转变成细小的纤维状或颗粒状结构；同时，Al-13Si合金的硬度提高43.2%，达到96.5HB，细化和变质效果明显。
关键字: Al-5Ti-1B-10Sr中间合金线材；细化；变质；微结构；硬度
（1. School of Physics and Technology, Wuhan University, Wuhan 430072, China;
2. Hunan Jinlianxing Special Materials Technology Co., Ltd., Yueyang 414005, China）
Abstract:The Al-5Ti-1B-10Sr master alloy wire (d 9.5 mm) was prepared by three-stage-feedstock method and hot extrusion process, with pure Al, K2TiF6, KBF4 and Al-20Sr master alloy (mass fraction, %) as raw materials. The wire surface is smooth, and without bubbles, peeling and cracks. The results show that, the Al4Sr phase is in the shape of block with many pores and cracks, and with an average size of 43.2 μm in length and 26.8 μm in width; the Al3Ti phase exhibits granular shapes with an average diameter of 14.4 μm; the TiB2 phase is very fine with an average size of 1.42 μm, and the percent of TiB2 particles with size no larger than 1.97 μm reaches 95.77%. When Al-5Ti-1B-10Sr is added into the Al-13Si alloy, not only the grain size of α(Al) is significantly refined, but also the eutectic Si phase changes from the coarse acicular into fine fibrous or granular. Compared with the untreated Al-13Si alloy, the hardness increases by 43.2% after adding Al-5Ti-1B-10Sr, up to 96.5HB, showing a good performance of both refinement and modification.
Key words: Al-5Ti-1B-10Sr master alloy wire; refinement; modification; microstructure; hardness
