High Damping Materials II

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Authors: Young Kook Lee, Young Seob Seo, Won Jin, Chong Sool Choi
Abstract: Effect of thermal cycling(γ↔ε) on γ→ε martensitic transformation kinetics and damping capacity of Fe-17mass%Mn alloy has been studied. The amount of ε martensite increases with thermal cycling in spite of decrease in Ms temperature. The increase in ε martensite content with thermal cycling is attributable to an increase in the density of martensite nucleation sites by introduction of dislocations during thermal cycling. The γ→ε martensitic transformation kinetics shows a burst mode in the non-cycled specimen, while the kinetics exhibits a sigmoidal mode in the cycled specimens. The damping capacity of the alloy increases with increasing the ε martensite content in the non-cycled specimen. On the contrary, the damping capacity of the alloy decreases with increasing the ε martensite content in the cycled specimens. The reason is that the dislocations introduced during thermal cycling, which obstruct the movement of the damping sources, become more with thermal cycling.
Authors: Fu Xing Yin, Satoshi Iwasaki, Takuya Sakaguchi, Kotobu Nagai
Abstract: M2052 alloy is a MnCu based high damping alloy that shows high damping capacity and the superior workability. In the present work, the microstructure and damping behavior of the alloy in different solidification cooling rates are investigated with directionally cast alloy plate. For the variation of solidification cooling rate in the range of 250~10K/s, the secondary dendrite arm spacing of the cast alloy changes from 4 to 18mm and grain size varies in the range of 100~200mm except the surface regions and center regions in the cast plate. As compared to the worked and heat treated alloy, the as-cast alloy shows a high temperature damping above the average phase transformation temperature of the alloy irrespective to the solidification cooling rate. On the other hand, a higher damping peak is observed in the cast alloy which is attributed much to the twin boundary damping, however, the magnitudes of the damping peak are found to be varied corresponding to the respective solidification conditions.
Authors: Jung Chul Kim, Seung Han Baik, Joong Hwan Jun, Young Kook Lee
Abstract: Effect of Cr addition on damping capacity, mechanical property, and corrosion resistance of Fe-18%Mn martensitic alloy has been studied. Martensite start temperature (Ms) of the alloy decreases linearly from 150 to 25 with increasing Cr content up to 15%. The damping capacity decreases gradually from 27 to 23% in SDC with increasing Cr content from zero to 10%, and decreases rapidly with further Cr content. The tensile strength of the alloy maintains a level of 60 / regardless of Cr content with an elongation of 20 to 25%. Immersion test in 5% NaCl solution leads to the result that the corrosion resistance of the alloy becomes excellent above 10% Cr. From the above results, it is concluded that the optimum Cr content to improve the mechanical property and corrosion resistance of the alloy with a lesser decrease in damping capacity is about 10%.
Authors: Joong Hwan Jun, Young Kook Lee, Jeong Min Kim, Ki Tae Kim, Woon Jae Jung
Abstract: We reports the damping properties of an Fe-23%Mn alloy with various amounts of thermal or deformation-induced ε martensite. By controlling cooling temperatures and cold rolling degrees, the volume fractions of thermal and deformation-induced ε martensites are changed from 33 to 50% and from 33 to 75%, respectively. The damping capacity of the Fe-23%Mn alloy increases with an increase in thermal ε martensite content, whereas the damping capacity associated with deformation-induced ε martensite shows a peak value at 57% of ε martensite. Transmission electron micrographs on deformed samples reveal that the decay of damping over 57% of deformation-induced ε martensite is caused by an introduction of perfect dislocations, which play a role in suppressing the movement of damping sources. For the same amount of ε martensite, deformation-induced ε martensite exhibits higher level of damping capacity than thermal ε martensite. This may well be owing to relatively greater length of γ/ε interfaces in response to higher number density of ε martensite plates.
Authors: Joong Hwan Jun, Young Kook Lee, Jeong Min Kim, Ki Tae Kim, Woon Jae Jung
Abstract: Microstructures and damping properties have been investigated in Fe-23%Mn-(0~2)%Si and Fe-23%Mn-(0~2)%Co alloys, based on experimental results from metallography, X-ray diffractometry and vibration test in a flexural mode. The amount and number density of ε martensite are increased with an increase in Co content, resulting in the improvement of damping capacity. For the same ε martensite content, the higher the Co content, the greater the damping capacity. On the contrary, an addition of Si affects to decrease the amount and number density of ε martensite, giving rise to a decay of damping capacity. The decreased ε martensite content by the addition of Si would be attributed to an increase in critical driving force for the γ→ε martensitic transformation by solution hardening effect.
Authors: K. Yamagami, Y. Kogo, T. Morizumi, H. Isono, T. Kosaka, K. Miyahara, N. Igata
Abstract: Based on the recent requirements, high strength, high damping stainless alloy HIDAS was developed. The chemical compositions are Fe-12%Cr-22%Mn and Fe-12%Cr-22%Mn-2%Co. After solution annealing, microstructure consisting of austenite fcc , martensite hcp  and bcc ’. When cold work was given,  and  increased. Damping capacity increased with the increase of  phase. The mechanism of high damping capacity would come from the hysteretic motion of Shockley partial dislocations which are lying at interphase interface of /. This alloy has also high strength. This is due to fine structure of /. Because of these properties, HIDAS can be applied to machinery industries.
Authors: Fei Yi Hung, Han Wen Chang, Zong Fu Chen, Truan Sheng Lui, Li Hui Chen
Abstract: Both Al-Zn alloy and Mg-Al-Zn alloy have been considered as high damping and light materials. For practical use, this study investigated the effects of the structure and the composition on the vibration fracture characteristics of the Al-xZn alloy and the Mg-xAl-Zn alloy under resonance. For Al-xZn (x=7, 11, 49, 83wt%) alloys, under both constant force and initial-deflection conditions, the 7Zn showed the greatest vibration life. For Mg-xAl-Zn (x=3, 6, 9wt%) alloys, experimental results indicate that the AZ31-F as-extruded samples showed a greater vibration life, while high Al fully-annealed samples (AZ91-O) had greater vibration fracture resistance under constant force conditions.
Authors: Terlize Cristina Niemeyer, Carlos Roberto Grandini, Sandra G. Schneider
Abstract: Recent studies have been done to achieve biomedical alloys containing non-toxic elements and presenting low elastic moduli. It has been reported that Ti-Nb-Zr alloys rich in beta phase, especially Ti-13Nb-13Zr, have potential characteristics for substituting conventional materials such as Ti-6Al-4V, stainless steel and Co alloys. The aim of this work is to study the internal friction (IF) of Ti-13Nb-13Zr (TNZ) alloy due to the importance of the absorption impacts in orthopedic applications. The internal friction of this alloy produced by arc melting was measured using an inverted torsion pendulum with the free decay method. The measurements were performed from 77 to 700 K with heating rate of 1 K/min, in a vacuum better than 10-5 mBar. The results show a relaxation structure at high temperature strongly dependent on microstructure of the material. Qualitative discussions are presented for the experimental results, and the possibility of using the TNZ as a high damping material is briefly mentioned.
Authors: Jin Cheng Wang, Zhong Ming Zhang, Gen Cang Yang
Abstract: Experiments have been carried out to investigate the damping behaviors of commercially pure aluminum (L2) prepared by equal-channel angular pressing (ECAP). The damping characterization was conducted on a DMTA-V apparatus. The internal friction was measured at frequencies of 0.1, 0.3, 1.0, 4.0 and 8.0 Hz over the temperature range of 20~150°C. The measured damping capacity shows that ultra-fine grained structure pure Al (L2) prepared by ECAP has a damping capacity that is enhanced in comparison with coarse one, especially when the temperature is higher than 60°C. The dependence of the damping capacity at room temperature on the strain amplitude shows a nonlinear characteristic, and increases rapidly with the strain amplitude (0) when 0 is comparatively low. While the strain amplitude is higher than certain value, the damping capacity will become saturated slowly. The high damping capacity of the pure Al prepared by ECAP was attributed to the high density of dislocations and ultra-fine grained structure.
Authors: Xiao Dong Tang, Jin Song Zhu, De Ping He
Abstract: Ultrasonic attenuation properties of two kinds of pored Al alloy were studied between 1MHz and 10MHz.. The results show that the ultrasonic attenuation properties are determined by the pore structures of Al alloy. Ultrasonic attenuation coefficient α in porous Al alloy increases with decreasing of pore diameter d, decreasing of porosity Ps , and increasing of specific surface area Sv. However the α in cellular Al alloy increases with decreasing pore diameter d, increasing porosity Ps and increasing specific surface area Sv. Ultrasonic attenuation property of cellular Al alloy is better than that of porous Al alloy when they have the similar pore diameter d and porosity Ps. The origin for different attenuation properties is discussed in these materials.

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