SLM工艺和循环热处理对Mn-30%Cu合金显微组织和硬度的影响  

Effects of SLM Process and Cyclic Heat Treatment on Microstructure and Hardness of Mn-30%Cu Alloy

作　　者：张溢辉 魏童博 苏晨昱 杨晶晶 王泽敏 Zhang Yihui;Wei Tongbo;Su Chenyu;Yang Jingjing;Wang Zemin(The Institute of Technological Sciences,Wuhan University,Wuhan430072,Hubei,China;Wuhan National Laboratory for Optoelectronics,Huazhong Universityof Science and Technology,Wuhan 430074,Hubei,China)

机构地区：[1]武汉大学工业科学研究院,湖北武汉430072 [2]华中科技大学武汉光电国家研究中心,湖北武汉430074

出　　处：《中国激光》2024年第20期233-244,共12页Chinese Journal of Lasers

基　　金：先进越野系统技术全国重点实验室开放基金(AF20240023)。

摘　　要：MnCu合金具有高阻尼、优异的形状记忆效应和易加工性,激光选区熔化成形(SLM)技术能够实现MnCu合金复杂结构的一体化制造,在汽车、航空航天、生物医疗和机器人等领域中有广阔的应用前景。采用SLM技术制造了Mn-30%Cu(30%为Cu的质量分数)合金,并研究了SLM工艺和随后的循环热处理的工艺参数对合金相对致密度、相组成、显微组织和硬度的影响。结果表明:在SLM工艺中的激光功率为196 W,扫描间距为0.06 mm,层厚为0.02 mm的情况下,当扫描速度为500~600 mm/s时合金的相对致密度(>99.7%)达到最高,当扫描速度低于500 mm/s时易形成气孔,当扫描速度高于600 mm/s时易形成未熔合孔洞缺陷。随着扫描速度由300 mm/s增加至700 mm/s,SLM成形过程中Mn元素的烧损量由16.4%降低至3.9%。成形的Mn-30%Cu合金主要由尺寸为0.5~1.6μm的γ-(Mn,Cu)相胞晶组成,随着扫描速度由300 mm/s增加到700 mm/s,胞晶尺寸先减小后增大。循环热处理后,胞晶由2~5μm和140~240μm两种尺寸的等轴混晶组成,同时,少量γ-(Mn,Cu)相发生马氏体相变,转变为γ′-(Mn,Cu)或析出α-Mn相。在显微组织和成分的综合影响下,相较于成形态,循环热处理后Mn-30%Cu合金的显微硬度值由143~153 HV降低到137~145 HV。Objective MnCu alloys,a shape memory alloy(SMA)type,exhibit good mechanical bearing performance,shape memory effect,damping performance,and low manufacturing cost.Furthermore,the alloys are easy to process.Therefore,MnCu-based SMA can potentially replace NiTi-based alloys in specific applications.Moreover,the alloy has application prospects in vibration reduction in aerospace,ships,vehicles,and machinery manufacturing.High manganese-type MnCu alloy(atomic fraction of Mn>70%)with high functional properties exhibits poor elongation.It is also readily brittle and oxidizes during high-temperature manufacturing.In the conventional manufacturing methods for MnCu alloys,complex structures such as lattice,inner channels,truss,and thin walls cannot be effectively completed.Hence,we select selective laser melting(SLM)to process MnCu alloy.SLM is a typical metal additive manufacturing technology.Different SLM manufacturing parameters and heat treatment methods significantly influence the properties of MnCu alloy samples.Therefore,in this study,we first study the influence of varying scanning speeds on the relative density of Mn-30%Cn alloy samples made from SLM to find a process window suitable for processing MnCu alloys.Second,we study the effects of SLM process parameters and cyclic heat treatment on the grain size,phase composition,phase structure,chemical composition,and microhardness of MnCu alloys.Finally,we obtain the comprehensive effects of SLM process parameters and cyclic heat treatment on the sample.Methods In this study,a planetary ball mill employs Al2O3 as a grinding medium to mix the Mn and Cu powders with 70:30 mass ratio.Then,we prepare cubic samples based on the mixed powders using the self-developed SLM instrument at different scanning speeds.Furthermore,we divide the Mn-30%Cu alloy prepared using SLM into two groups;one has cyclic heat treatment,and the other does not.The scanning tracks and grains on the surface of the sample are observed using an optical and electron microscope at different magnificat

关 键 词：MnCu合金 激光选区熔化 循环热处理 显微硬度 

分 类 号：O436[机械工程—光学工程]