| 摘要 |
1,264,053. Zone melting. UNITED AIRCRAFT CORP. 9 March, 1970 [13 March, 1969], No. 11115/70. Heading B1S. [Also in Division B3] Apparatus for casting an article with a selected grain orientation comprises a chill plate 10, a mould 12 having an extension 14 opening onto the chill plate, and heating means 22, 24, 26, 28 and 30 arranged so as to provide a lateral thermal gradient from the downward extension to the parts of the mould laterally remote therefrom. After pouring the metal into the mould, coolant is supplied to the chill plate 10 to cause formation of vertically orientated directionally solidified grains in the extension 14. When solidification reaches the position represented by line 34, a radial thermal gradient is produced in the disc portion of the mould by gradually reducing the heating effect from the axis outwardly toward the periphery of the disc. This causes grain growth in a radial direction and produces a [0,1,0] radial orientation and a [1,0,0] tangential orientation. A seed (36) made up of wedges (38) each having the desired orientation for the portion of the disc extending outwardly therefrom may be provided at the bottom of the extension 14. In an embodiment, Fig. 6, the mould is made up of individual mould elements 50 extending radially outward from a central cavity 52 surrounding a vertical cylindrical chill 54. The chill is surrounded by seed segments 56, one for each mould element 50. A radial orientation of the grains is obtained throughout the mould. The alloy is poured at a temperature at least 100‹C above its melting point. |
