| 摘要 |
Process for prodn. of monocrystalline products consisting of casting molten metal into a mould with a cooled base, then after the initial formation of the crystal which forms as a result of cooling, carrying out the crystallisation process proper by progressively cooling the mould from the bottom to the top. The product is obtd. in a mould with two cavities, i.e. an upper main cavity having the shape of the product, and a lower contiguous auxiliary cavity in the form of a truncated cone with the large base downwards and a wedge-shaped projection close to its large base. Conditions of sudden over-cooling are created by a refrigerator at the point of the wedge shaped projection to produced a single natural crystal nucleus in the point and rapid growth of the crystal along the contour of the base. Method is suitable for prodn. of turbine blades, permanent magnets, etc. |
