激光选区熔化（SLM）3D打印非晶合金及其结构演变与性能调控

Amorphous alloys (also called as metallic glasses) are a novel type of metallic materials developed in the middle of last century; they are regarded as one of the most important engineering materials in the new century due to the good combination of a series of excellent properties benefiting from the disorder atomic structure. However, the big challenge to industry application of amorphous alloys is the extreme difficulty in forming and manufacturing at room temperature. Development of new manufacturing approaches becomes crucial for the future applications of amorphous alloys. Selective Laser Melting (SLM) 3D printing technique developed in recent years seems to be a promising method to solve this problem. However, the interaction mechanism between laser and amorphous alloys and the principle of the SLM manufacturing have yet been well understood due to the fact that amorphous alloys own totally different atomic structure with respect to the conventional crystalline metallic materials. In this project, a typical Fe-based and Zr-based amorphous alloy powders with great glass forming ability are selected. Then, detailed studies will be carried out on the interaction processes between laser beam and the amorphous powders and the effect of SLM processing parameters (such as laser energy density, scanning rate and powder surface modification) on the formability, microstructure and properties of the SLM formed compounds. Based on the researches, we hope to clarify in detail the SLM forming mechanism of the amorphous alloys. Finally, via the optimization of the SLM processing parameters, aiming to the alleviation of residual stress and suppression of forming defects, we hope to prepare a few high-quality amorphous compounds. It is envisaged that the success of the present research project can break through the bottle-neck of manufacturing of amorphous alloys, and consequently extend considerably the application scope of this new type of metallic materials.

非晶合金是上世纪中叶发展起来的一种新型金属材料，因其具有长程无序的原子结构而拥有一系列优异性能，被认为是21世纪最重要的工程材料之一。然而，非晶合金在室温下难以成形加工是制约这类材料工程应用的瓶颈。发展新的成形技术是非晶合金未来发展与应用的关键。近年来发展起来的激光选区熔化(SLM) 3D打印技术有望解决非晶合金的成形难题。由于非晶合金具有与晶态材料完全不同的原子结构，激光与非晶相的交互作用及非晶合金SLM成形机理尚不清楚。本项目拟选择具有强非晶形成能力的Fe基和Zr基非晶粉末为对象，系统研究SLM成形过程中激光与非晶粉末的交互作用机理；SLM成形非晶合金过程中的温度梯度及残余应力形成机制、分布特征及调控方法；以及SLM成形非晶合金的微结构及性能的演变规律。通过工艺优化，抑制残余应力，制造出高性能非晶合金零件。本项目的研究对突破非晶合金成形加工瓶颈，促进其工程应用具有重要的科学和工程意义。

自1960年非晶合金诞生以来，制造大尺寸和复杂形状非晶合金一直是材料科学家追求的目标。然而，非晶合金有限的玻璃形成能力以及较差的机械加工性能使得这类材料仍难以大规模工程应用。近年来快速发展起来的3D打印技术为解决本领域上述卡脖子难题提供了新思路。在基金委的资助下，本项目围绕3D打印非晶合金这一主题，开展了以下八个方面研究：适合于非晶合金增材制造的3D打印装置研制、SLM成形非晶合金及其微结构演变、SLM 3D打印非晶合金的缺陷形成机制及控制、SLM成形非晶合金的残余应力测量与模拟、SLM 3D打印成形非晶基复合材料及其力学性能、基于非晶相强化的SLM 3D打印金属基复合材料、SLM 3D打印非晶合金的功能特性以及非晶合金3D打印成形新技术。获得的代表性研究成果如下：（1）揭示了高能束激光3D打印条件下非晶合金的微结构特征与演变规律，提出了适用于SLM技术的非晶合金成分遴选新判据。（2）揭示了3D打印非晶合金中孔洞与微裂纹的形成机制，提出了扫描策略、添加晶态韧性相等策略大幅降低甚至完全避免微裂纹的产生。（3）开发了若干高强度且具有良好塑性的3D打印非晶基复合材料，以及基于非晶相强化的3D打印晶态复合材料，揭示了其强韧化机制。（4）开发了若干高活性、可长效循环使用的3D打印非晶合金催化剂，实现高效污水降解。（5）开发了一种非晶合金3D打印成形新技术-超音速喷涂3D打印，成功制备出大尺寸、高韧性Fe基非晶合金及复合材料构件。本项目在Journal of Materials Chemistry A, ACS Applied Materials & Interfaces, Additive Manufacturing, Scripta Materialia等高水平期刊发表论文36篇，研究工作在国际上有一定影响。受邀撰写3D打印非晶合金的综述1篇（Mater Sci Eng. R）。获授权专利5项，获省部级二等奖2项。本项目的研究对突破非晶合金成形加工瓶颈，促进非晶合金的实际工业应用具有重要的科学意义和工程意义。