Al-3%Si合金等径角挤压的变形行为

Deformation behavior of alloy Al-30%Si due to equal course-angle protrusion

采用A路径对内部含有铜片的Al-3%Si合金在室温下进行5道次等径角挤压来考察其对材料宏观和微观组织影响.通过示踪法研究铜片位置的变化,通过SEM和OM观察脆性相Si的变化,并对材料进行XRD分析.结果表明:经5道次变形后铜片发生偏转至45°,铜片自身也发生了扭曲变形,证明剪切作用下,存在着扭转力;共晶Si的变化行为是在1道次挤压后共晶Si呈长条状分布在晶界;2道次挤压后长条状共晶Si被破碎成短杆状,部分偏离晶界;4道次挤压后短杆状共晶Si被破碎成块状,弥散分布在基体上;5道次挤压后块状共晶Si发生了偏聚,平均尺寸由10μm变为3μm,并在垂直剪切方向上存在明显移动;晶面取向(220)的衍射峰强度逐步降低,而(111)晶面的衍射峰强度则明显增加,主导取向由(220)变为(111),晶面取向(200)和(311)变化不明显.

The alloy Al-3% Si, containing copper slice within itself, after 5-pass equal course-angle protrusion with A-passage at room-temperature was used to investigate the effect of ECAP on the microstructure of materials. The position change of copper slice was investigated by using the tracing method, the variation of brittle phase Si was observed with SEM and OM, and the material was analyzed with XRD. The result showed that after protrusion of five passes, the copper slice deflected to 45° and torsional deformation took place with itself, showing that, under shearing action, the torsional force would exist together with the variation of eutectic Si as follows： after first pass of protrusion, the eutectic Si would exhibit strip-shaped and distribute on the crystalline boundary; after the second, the strip-shaped eutectic Si would be broken into short bars and a portion of them would move off from the crystalline boundary; after the fourth, it would become blocks and distributed onto the matrix; and after the fifth, off-aggregation of the blocked eutectic Si took place, its average size changed from 10 btm into 3 μm, and there was obvious displacement in the direction perpendicular to the shearing. The diffraction peak intensity of the crystalline surface orientation （220） was gradually decreased while that of （111） crystalline surface obviously increased. The dominant orientation changed from （220） into （111） and the change of crystalline surface ori- entation （200） and （311） was unnoticeable.