激光增材制造Ni-Cr-Al基础合金系组织与性能研究  

Microstructure and Properties of Ni-Cr-Al Basic Alloys Fabricated by Laser Additive Manufacturing

作　　者：于群[1] 王存山[1] 董闯[1] Yu Qun;Wang Cunshan;Dong Chuang(Key Laboratory for Materials Modification by Laser Ion and Electron Beams Ministry of Education,Dalian University of Technology,Dalian 116024,Liaoning,China)

机构地区：[1]大连理工大学三束材料改性教育部重点实验室,辽宁大连116024

出　　处：《中国激光》2022年第14期40-51,共12页Chinese Journal of Lasers

基　　金：国家自然科学基金(51371041)。

摘　　要：基础成分是镍基高温合金向多元合金演化的关键。因此,以Ni-20%Cr(20%为质量分数)合金为基础,以Al为合金化元素,利用团簇模型设计5种具有代表性的基础合金成分。系统分析激光增材制造非平衡凝固条件下合金组织和性能随成分的演化规律。结果表明,随着Al含量的增加,沉积态合金的基体组织逐渐由γ-Ni固溶体向γ′-NiAl有序相转化,而沿晶界分布的α-Cr固溶体在数量稳定增加的同时,其形态也由颗粒状变为链条状,且在Al含量(原子数分数)为25.0%时被γ′-NiAl+γ-Ni离异共晶组织所取代。合金强化机制由固溶强化向沉淀强化的转变,致使沉积态合金的硬度和强度随着Al含量的增加而逐渐增强,而塑性则逐渐降低。增加Al的含量有利于提高沉积态合金的抗高温氧化性能,但过高Al含量会损害合金的可焊性。因此,优质基础合金中Al的含量应限制在12.5%~18.5%范围内,以使合金兼有良好的力学性能、高的抗高温氧化性和好的可焊性。Objective Ni-based superalloys are the ideal high-temperature materials due to their excellent oxidation resistance and microstructure stability at the elevated temperature.But the technical characteristic and limitation of traditional manufacturing techniques restrict the development and product of superalloy components.Recently,the laser additive manufacturing(LAM)technology provides an effective tool to fabricate the integral and complex components.However,the compositions of heritage alloys are designed based on the traditional techniques without considering the specifications of the LAM process.During the LAM process,the non-equilibrium characteristics of multiple thermal cycles,rapid heating and cooling rate and the localized microstructural evolution result in the metallurgical defects such as cracks,pores,and lack of fusion,which are difficult to be completely eliminated by optimizing the process parameters.Note that the Ni-based superalloys are developed from the Ni-20%Cr alloy,and the Ni-Cr-Al system can be regarded as the basic composition of the Ni-based superalloys.The basic composition plays a significant role in the further design of multicomponent alloys owing to the correlation to the microstructural stability,mechanical properties and weldability of Ni-based superalloys.Therefore,it is necessary to optimize the compositions by investigating the influence of Cr and Al contents on microstructures and properties of the basic alloys.In this paper,five representative basic alloys are designed based on alloying of binary Ni-20%Cr alloy with Al element,and the influence of composition on microstructures and properties of as-deposited alloys is systematically investigated.This research can be helpful to design the Ni-based superalloys which are fit for the LAM process.Methods Five basic alloys are first designed through the“cluster-plus-glue-atom”model,and then fabricated by the LAM process.The pure Ni plate is chosen as the substrate.The elemental powders of Ni,Cr and Al with purity(mass fraction)o

关 键 词：激光技术 激光增材制造 镍基高温合金 基础成分 组织 性能 

分 类 号：TG132.32[一般工业技术—材料科学与工程]