球硅Al-22Si活塞合金金相组织及使用性能的研究

The Structure and Properties of Nodular Silicon Al-22Si Alloy for Pistons

过共晶Al 225合金经特殊变质处理后,初生硅及共晶硅皆细化,再经过l处理,硅相将发生片(块)向球化转变过程,从而获得球硅A122Si合金。图象分析表明,硅相平均长宽比为二.6,99％的硅相直径在30W以下,只有1％以下的球硅直径在30～40W。球硅A122Si合金具有较好的塑性,室温抗拉强度达到300MP,573K抗拉强度达到100MP,远高于常见AI-22St活塞合金性能。比之常见过共晶A122Si合金,球硅A122Si合金切削性能得到明显改善。

The eutectic and primary silicon in hypereutectic Al-Si alloy can be refined by special modification. Then, the nodular silicon hypereutectic Al-Si alloy can be obtained through T6 treatment due to the crystallography flaky-nodular silicon transition. The average aspect ratio of nodular silicon is about 1. 6. In this alloy 99% of the silicon particles have their diameters less than 30 um, and less than 1 % of them have their diameters ranged from 30~40um. The nodular silicon Al-22Si is characterized with better plasticity and with an ultimate tensile strength at room timperature up to 300 MPa and a tensile strength at 573K up to 100MPa, being better than those in commercial Al-22Si piston alloy. By way of contrast with commercial hypereutectic of Al-Si alloy the machinability Al-Si alloy tested was improved greatly.