【作者】 丁胜；

【导师】 李宁；

【作者基本信息】 四川大学 ， 材料加工工程， 2007， 硕士

【摘要】 阻尼合金是一种具有减振降噪特性的功能材料。在现有的几类阻尼合金中，Fe-Mn系阻尼合金不但强度较高、成本低，而且其阻尼性能随着应变振幅的增大而增加，可作为较大振动和冲击部件使用，应用前景非常好，因此在近年来引起国内外研究学者的广泛重视。本文采用真空熔炼技术制备了Fe-18Mn、Fe-17Mn-2Cr、Fe-16Mn-6Cr三种合金进行相关研究。采用JN-1型倒扭摆内耗仪测试了三种合金阻尼性能；利用NETZSCH DSC204型DSC测试其的相变点；利用Olympus光学显微镜、日本产JSM-5900LV型扫描电镜和H-700H型透射电子显微镜观察分析其显微组织；利用X射线衍射对合金进行物相分析；在3％NaCl溶液（人工海水）中对18-8不锈钢、Fe-18Mn、Fe-17Mn-2Cr和Fe-16Mn-6Cr进行腐蚀实验，并用失重法标定试样的耐腐蚀性。具体进行了如下研究：Fe-18Mn合金的对数衰减率几乎都是随扭转应变量的增加成近似线性增加，且在扭转应变为6×10^-4时未出现峰值；随固溶温度的升高，Fe-18Mn合金的阻尼性能随之变好，1000℃时达到峰值。因为经1000℃固溶后，合金中ε马氏体的数量最多且片层最薄，阻尼源最多，所以阻尼性能最好。Fe-Mn合金经1000℃固溶处理后，再做深冷处理，提供了γ→ε继续转变的驱动力，使得残余γ奥氏体转变为ε马氏体，增加ε马氏体的数量，进一步提高了合金的阻尼性能。随Cr的加入Fe-Mn合金Ms点基本相当，因为加入合金元素Cr的同时降低了Mn含量；Fe-17Mn-2Cr和Fe-16Mn-6Cr的阻尼性能低于Fe-18Mn合金，但降低的不多，因为随Cr的加入会使Fe-Mn合金晶格发生畸变，对阻尼源有一定钉扎作用，阻碍阻尼源的运动；一定的变形会提高Fe-Mn-Cr合金的阻尼性能，在4％预变形量时，阻尼性能最好，因为4％变形应力诱发的ε马氏体对阻尼性能的提高远大于产生的位错对阻尼性能的负面影响；Fe-Mn合金中加入合金元素Cr，不但保持了很高的阻尼性能，还增加了合金的耐蚀性能，随Cr含量的增加耐蚀性愈好；Fe-Mn合金随Cr的加入，因固溶强化进而提高了抗拉强度，但对塑性影响很小。Fe-18Mn合金经ECAP后，因发生了真应变为0.67的大变形而丧失了阻尼性能，随退火温度的升高阻尼性能随之变好，至到900℃阻尼性能达到最好，对数衰减率比未ECAP试样提高近82％，且明显好于未ECAP。因为Fe-18Mn合金ECAP加900℃退火后，带状组织消失，高密度位错得到回复，ε马氏体片层比未经ECAP状态的更多更细小，γ／ε界面最平整，所以合金的阻尼性能显著增加。由此可见，ECAP是提高Fe-Mn合金阻尼性能的一种有效方法。更多还原

【Abstract】 Damping alloys are functional materials which can be applied on components thatrequire low levels of sound emission and vibration. Among the damping alloys,Fe-Mn alloys have better strength and lower price, and its damping capacityincreases with the strain amplitude, so this alloy can be used as the highly vibratingand shocking parts and has a better application prospect. So Fe-Mn damping alloyshave attracted more attention for these years. The work was conducted with threedamping alloys melt in vaccum induction melting furnace, including Fe-18Mn,Fe-17Mn-2Cr, Fe-16Mn-6Cr alloys.The JN-1 reversal torsion pendulum device was applied to investigate the dampingcapacity of the alloys. The Olympus microscope, transmission electron microscope（TEM） and H-700H electron microscope were used to analyze the microstructure ofthe alloys annealed at different temperatures. The phases of the alloy weredetermined using Philip X’Pert Pro MPD X-Ray diffraction instrument. Thecorrosive properties of 18-8,Fe-18Mn,Fe-17Mn-2Cr and Fe-16Mn-6Cr were testedusing loss-in-weight method in 3%NaCl solution. The following respects of thealloys were investigated in this paper.The logarithmic decrement of Fe-18Mn alloy increase linearly with increasing thestrain amplitude, and there is no peak value when the torsional strain amplitudeγ_maxis 6×10^-4. The damping capacity of Fe-18Mn alloy increase with raising of solutiontreatment temperature, reaching its maximum around 1000℃.Because Fe-18Mnalloy is solution treated after 1000℃,the quantity ofε-martensite is most and itsplates is thinnest, damping sources is most, damping capacity is highest. Cryogenictreatment after solution treated at 1000℃supply driving force of transformationγ→ε,so increasing the quantity ofε-martensite, and the damping capacity is furtherincreased. Fe-Mn alloys’ Ms temperature is nearly identical with increasing Cr content,because of decreasing Mn content with increasing Cr content. The damping capacityof Fe-17Mn-2Cr and Fe-16Mn-6Cr alloys is lower than it of Fe-18Mn alloy a little,because crystal lattice of Fe-Mn alloys aberrant with increasing Cr content, crystallattice aberrance anchor damping sources and obstruct its anelastic movement.Proper deformation can raise the damping capacity of Fe-Mn-Cr alloys, reaching itsmaximum around 4%, because anisotropic martensite raising damping capacity, andthe dislocations introduced during deformation deteriorate the damping capacity, butthe anistropic mantensitic contribution to damping capacity bigger than deteriorationof dislocation. And Cr raising the erosion resistance of Fe-Mn alloys. The tensilestrength is raising with increasing Cr content because of solution strength, but theaffection for plasticity is small.Fe-18Mn alloy after ECAP lose the damping capacity because of deformation withtrue strain 0.67. The damping capacity increase with raising annealing temperature,reaching its maximum around annealing temperature at 900℃, this maximum is 82%more than Non-ECAP sample. By annealing at 900℃, the high density dislocationsof Fe-18 alloy have been recovered, the stacking faults can vanish completely,therefor the number ofε-martensite plates is more and the damping sources increase,and the damping capacity of the alloy is improved. It can be see that ECAP is anaffective method.更多还原