A new approach to predicting precipitation sequences in rapidly solidifying metallic alloys

制造合金制品的多种方法大致可以分为减法制造、粉末冶金和加法制造(3D打印)。 前两个实践是成熟的；它们只经历了逐步的增强。第三个不同。同行评议的期刊和普及科学、工程和技术的杂志的内容证明，加法制造已经取得了很大成就，3D打印已经从一种奢侈的生产方式转变为一种有用的生产方式。对于高质量的非金属零件，这一结论反映了实际情况，但添加金属合金的力学性能比传统制造的要差。原因有很多；其中一个原因在其重要性上显得格外突出。金属粉末的混合物被放置在部分制造的物体的表面作为新的层，这种团聚被强大的激光束击中。这种冲击会导致涂层瞬间融化，然后在寒冷的衬底表面固化。这种冻结的速度太快，不能在格列佛-舍尔范式下处理；它不会太快导致无定形状态。在3D打印中，伴随着重复步骤的快速凝固是一种独特的过程，它导致过冷熔体，由此可能形成亚稳定相，从而产生拜占庭组织，其结晶学和成分特征可以使用现代表征工具确定。这些信息对于印刷后性能增强热处理的智能设计至关重要。 然而，最终的目标不是描述印刷后的微观结构，而是获得一种预测铝、钛和铜合金以及其他具有广泛成分调制的多组分金属系统的能力，这最终可能在添加剂制造中尝试。这种能力不能基于爱迪生的方法；它必须建立在体面的科学基础上，而不是建立在朴实无华的经验主义之上。 2010年，申请人推测，如果热力学上可能的相的组成接近于剩余液体的组成，那么这些相的沉淀将被促进，因为它们在过冷熔体中的形核不需要缓慢的长期扩散。这一想法可以理解Al-Fe-Si熔体快速凝固的结果，但它对各种多组分系统的适用性从未得到认真的测试。 建议使用现有的熔体旋转器快速凝固化学和成分不同的金属熔体，然后判断“成分相似”假说的可行性。如果它的实用性得到证明，那么这个假设将成为一个物理上合理的、计算上简单的预测通过加法制造生产的金属物体的微观结构的指标。

Numerous ways in which objects made of alloys are produced can roughly be divided into subtractive manufacturing, powder metallurgy, and additive manufacturing (3D printing). The first two praxes are mature; they undergo only gradual enhancements. The third one is different. Contents of peer-reviewed journal and magazines popularising science, engineering and technology attest that so much has been already achieved in additive manufacturing that 3D printing has transformed from an extravagantness to a useful production method. For high quality non-metallic parts, this conclusion reflects the reality, but mechanical properties of additively made metallic alloys are worse than of those made traditionally. Reasons are numerous; one of them stands apart in its importance. A mixture of metallic powders is placed on a surface of a partially fabricated object as a new layer, and this agglomeration is hit by a powerful laser beam. This impact causes an instantaneous melting of the layer followed by its solidification on a cold substrate's surface. This freezing is too fast to be treated within the Gulliver-Scheil paradigm; it is not too quick to result in an amorphous state. Rapid solidification accompanying repetitive steps in 3D printing is a distinctive process leading to supercooled melts, from which metastable phases may form, and therefore to byzantine microstructures whose crystallographic and compositional features can be ascertained using modern characterization tools. This information is vital for an intelligent design of post-printing properties-enhancing heat treatments. The ultimate goal, however, is not to describe post-printing microstructures, but to acquire an ability to predict them for Al, Ti and Cu alloys as well as for other multicomponent metallic systems with wide compositional modulations, which may eventually be tried in additive manufacturing. Such an ability cannot be based on the Edisonian approach; it must rest on a decent scientific foundation rather than on an artless empiricism. In 2010, the applicant conjectured that if compositions of thermodynamically possible phases are close to the composition of a remaining liquid, then the precipitation of these phases would be facilitated, because their nucleation within a supercooled melt will not require a slow long-range diffusion. That idea allowed to comprehend outcomes of rapid solidification of Al-Fe-Si melts, but its applicability to various multicomponent systems was never seriously tested. It is proposed to use an available melt spinner for rapid solidification of chemically and compositionally dissimilar metallic melts, and then to judge on the "compositional similarity" hypothesis feasibility. If its practicality is demonstrated, then the hypothesis will become a physically sound and computationally simple predictor of microstructures of metallic objects produced via additive manufacturing.