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以（80％石英砂＋20％石英玻璃粉）＋3％H3BO3（均为质量分数，下同）为坩埚涂层材料，烧结后获得厚3mm的表面光洁、无裂纹玻璃态涂层在该涂层中熔炼Cu—39Ni—6Fe和Ni—30Cu—5Fe合金，分别获得了190K和210K的大过冷度，超过了晶粒骤然细化的临界过冷度ΔT2．以硅溶胶为粘结剂，石英玻璃粉为面涂层的铸型，浇铸后进行一次过热，使Ni—30Cu—5Fe合金获得了100K过冷度，超过了该合金负温度梯度下实现定向凝固的临界过冷度ΔT1。
The crucible coating material was composed of (80% quartz sand + 20% quartz glass powder) + 3% H3BO3 (both mass fractions, the same below) and sintered to obtain a smooth and crack-free glass coating having a thickness of 3 mm in the coating Melting of Cu-39Ni-6Fe and Ni-30Cu-5Fe alloys resulted in large undercooling of 190K and 210K, respectively, which exceeded the critical undercooling ΔT2 of sudden refinement of grains. The silica sol as a binder, the quartz glass powder for the topcoat casting mold, after casting one overheating, Ni-30Cu-5Fe alloy obtained 100K undercooling, exceeding the alloy negative temperature gradient to achieve directional solidification The critical undercooling ΔT1.