梯度相变结构FeCoCrNiMn高熵合金的制备、结构演变及变形机制

高熵合金是一种新的合金设计理念。与传统合金相比，高熵合金具有更高的低温强度和断裂韧性，良好的耐腐蚀性等，已经成为材料科学和凝聚态物理的研究热点。早期发展的高熵合金具有单相的面心立方结构或者单相的体心立方结构。具有面心立方结构的高熵合金通常塑性较好，但强度较低；而具有体心立方结构的高熵合金强度较高，但塑性相对较差。如何协调强度与塑性二者之间的关系，同时获得高强度和高塑性是目前高熵合金研究的重点。本项目拟在前期工作的基础上，结合相变诱发塑性和制备梯度结构材料两种方法，发展同时具有高强度和高塑性的梯度相变结构高熵合金，研究内容包括：①制备梯度相变高熵合金，确定制备工艺参数对梯度相变结构形成的影响；②确定马氏体相变以及逆马氏体相变的机制；③阐明梯度相变结构特征与合金力学性能的关系；④阐明梯度相变结构高熵合金的变形机制与强韧化机理。研究结果将为设计和制备高强度、高塑性的高熵合金提供理论基础和依据。

High-entropy alloy is a new alloy design concept. Compared to traditional alloys, high-entropy alloy has higher low-temperature strength and fracture toughness, and good corrosion resistance, etc. It has become a research hotspot in material science and condensed matter physics. The high-entropy alloys developed in the early stage have a single-phase face-centered cubic structure or a single-phase body-centered cubic structure. High-entropy alloys with face-centered cubic structure usually have good plasticity but low strength, while high-entropy alloys with body-centered cubic structure have good strength but low plasticity. How to coordinate the relationship between strength and plasticity, and obtain high strength and plasticity simultaneously is the focus of high-entropy alloys research at present. On the basis of our previous work, this project intends to develop gradient phase transformation structured high-entropy alloys with both high strength and large plasticity by combining transformation-induced plasticity and preparation of gradient structure materials. The research contents include: (1) fabricating gradient phase transformation high-entropy alloys, and determining the influence of preparation parameters on the formation of gradient transformation structure; (2) determining the mechanisms of martensitic phase transformation and inverse martensitic phase transformation; (3) revealing the relationship between the structural characteristics of gradient phase transformation and the mechanical properties of the alloy; and (4) clarifying the deformation mechanisms, and strengthening and toughening mechanisms of the gradient phase transformation high-entropy alloy. The research will provide theoretical basis and scientific basis for the design and preparation of the high-entropy alloys with high-strength and high-plasticity.