单元素基合金表面激光高熵合金化研究

High entropy alloys with multi-principal elements are advanced materials for the surface coating because of its simple structure and excellent performance of wear-resisting, corrosion resistant, stable organization comprehensive characteristic. This investigation is based on the excellent properties of high entropy alloy, put forward the high entropy alloying layer of three different components, with special properties were fabricated established on Ni-based, iron base and copper matrix three single element base alloy with laser surface alloying method, and it is studied to the phase formation and the phase transformation mechanism of the low entropy alloy passing the middle entropy into the high entropy alloy and the base material and alloying elements influence on the formation and the performance of the high entropy alloy under laser rapid melting solidification condition alloy; Study laser rapid solidification condition the influence on the alloy entropy change process and the organization and the performance characteristics of the high entropy alloy, the non-equilibrium solidification crystalline forms of the high entropy alloy and the role of solidification rate, etc; Research the hardness of the high entropy alloying layer, high temperature softening resistance, high temperature oxidation, heat corrosion, electrochemical corrosion, abrasion and related performance characteristics and control mechanism, thus enrich and develop the theory system of specific performance coating of the high entropy alloy, for the development of independent innovation of China's new laser engineering materials of high entropy alloying protection technology and the high entropy alloy laser direct forming laid the experiment and theoretical foundation.

多主元高熵合金结构简单、性能优异，具有耐磨、耐蚀、组织稳定的综合特性，是表面涂层首选的先进材料。本课题基于高熵合金的优异性能，提出在镍基、铁基与铜基三种单元素基合金表面采用激光合金化方法建立起三种不同成分、具有特定性能的高熵合金化层，并由此研究在激光快速熔化凝固条件下低熵合金经过中熵合金过渡到高熵合金的相形成与相转化机制，基材和合金化元素对高熵合金形成与性能的影响；研究激光快速凝固条件对合金熵变过程及对高熵合金组织与性能特征的影响，高熵合金非平衡态凝固结晶的形式、凝固速率的作用等；研究高熵合金化层的硬度、高温软化抗力、高温氧化、热腐蚀、电化学腐蚀和磨损等相关性能特征与调控机制等，由此丰富和发展高熵合金特定性能涂层理论体系，为发展我国自主创新的工程材料新型激光高熵合金化防护技术和激光高熵合金直接成形奠定实验和理论基础。

单元素基合金(Single-element base alloy，缩写SEBA)材料在热力学平衡相图上是处在某一主元素一端，其显微结构的典型特征为固溶体(置换固溶体或间隙固溶体)或固溶体上分布着第二相颗粒，基相主要强化方式有固溶强化、细晶强化、脱溶强化、第二相弥散强化以及相变强化等。由于SEBA是由单一主元素通过低合金化或高合金化形成的，其物理化学性能及力学性能呈特定性与专用性，很难实现高强度、高硬度、高耐蚀性等多种性能的综合，因此限制了它们在一些极其复杂与恶劣环境下的应用。多主元高熵合金结构简单、性能优异，具有耐磨、耐蚀、组织稳定的综合特性，是表面涂层首选的先进材料。本课题基于高熵合金的优异性能，提出了在镍基、铁基与铜基三种单元素基合金表面采用激光合金化方法建立起三种不同成分、具有特定性能的多种高熵合金化层。主要研究内容：（1）在激光合金化快速熔化凝固条件下，低熵合金经过中熵合金过渡到高熵合金的相形成与相转化机制，Fe、Ni、Cu合金基材主元素和合金化粉体材料对高熵合金形成与性能的影响；（2）激光快速凝固条件对合金熵变过程及对高熵合金组织与性能特征的影响，高熵合金非平衡态凝固结晶的形式、凝固速率的作用等；（3）高熵合金化层的硬度、电化学腐蚀、磨损和磨蚀等相关性能特征与调控机制等，由此丰富和发展高熵合金特定性能涂层理论体系，显著提高了SEBA材料的表面性能，为发展我国自主创新的工程材料新型激光高熵合金化防护技术和激光高熵合金直接成形奠定实验和理论基础。