超重力对Al-6%Cu合金凝固组织的影响

利用离心旋转加热炉研究了超重力对Al-6%Cu合金凝固组织细化及析出相形貌的影响. 结果表明，超重力场可细化晶粒，在常重力条件下(重力系数G=1)，初生铝相主要为粗大的等轴晶，晶粒直径为112 mm；在超重力条件下，当G分别为100, 300, 500和700时，晶粒直径分别减小为85, 77, 70和63 mm，晶粒细化，且超重力越大晶粒细化越明显. 超重力场可改善Al2Cu析出相的形貌，有效提高合金性能，G=1时Al2Cu相主要为粗大的不规则块状，合金硬度为59.9 MPa；当G分别为100, 300, 500和700时，Al2Cu相逐渐转变为细小的块状和球状，硬度分别增大为68.4, 73.2, 74.4和74.9 MPa，且超重力越大，Al2Cu相越细小、致密，合金的硬度也越高.

Effect of Super-gravity Field on Solidification Structure of Al-6%Cu Alloy

The effect of super-gravity on the refining of solidification structure and morphology of Al2Cu in Al-6%Cu alloy was studied by selecting the central part of the sample after processing by a centrifugal high temperature furnace. The results showed that the grains could be refined under super-gravity field. Al primary crystals in the alloy were the bulky equiaxed crystals with a diameter of 112 mm under the gravity coefficient G=1, and the grain diameter decreased to 85, 77, 70 and 63 mm as the gravity coefficient G increased to 100, 300, 500 and 700, respectively, indicating that the grain was remarkably refined as G increased. Moreover, super-gravity field could improve the morphology of Al2Cu precipitates and the properties. Al2Cu precipitates were bulky irregular block and the value of hardness was 59.9 MPa under G=1, and then they transformed into tiny lump and spheres gradually as G increased to 100, 300, 500 and 700, respectively. As a result, the value of hardness increased to 68.4, 73.2, 74.4 and 74.9 MPa, respectively. Smaller and denser Al2Cu precipitates formed as the super-gravity increased, which also improved the hardness of the alloy.