ZL205A合金块状偏析形成机理

Formation Mechanism of Massive Segregation of ZL205A Alloy

摘要:

以实际生产过程中ZL205A合金铸件块状偏析缺陷为研究对象，研究了该合金块状偏析显微组织和偏析相的化学成分，并研究块状偏析相的显微硬度及其对力学性能的影响。结果表明：ZL205A合金块状偏析是由Al3Ti、Al3V和Al3Zr组成的混合组织，显微组织呈规则的长方形或花瓣状，偏析缺陷对试样抗拉强度和延伸率影响较大，但偏析相显微硬度比基体高，热处理并不能消除块状偏析；块状偏析是在合金液凝固结晶过程中，Al3Ti、Al3V和Al3Zr形核质点聚集、长大造成的，预制锭中粗大的块状组织对其形成具有一定的形态遗传性。

Abstract:

Segregation defect of ZL205A alloy casting during practical production process was researched. The microstructure of the segregation, the compositions and the microhardness of the segregation phase, and the effect of segregation defect on the mechanical properties of the casting were studied. The results reveal that the chemical compositions of the segregation phase are Al3Ti, Al3V and Al3Zr, and the microstructure is in the form of rectangle or petal shape. The segregation defect has an obvious effect on the tensile strength and the elongation. But the microhardness of the segregation phase is higher than that of the matrix. Hot treatment can not eliminate the segregation. Actually the massive segregation belongs to the microsegregation. It is caused by downward movement of Al3Ti, Al3V and Al3Zr of heterogeneous nucleation particle to agglomerate during solidification. And the coarse massive structures in the ingot casting have certain morphological heredity in its formation.