Ta—O固溶体中的Snoek—Koster驰豫

试样表面镀一薄层Ｔｉ，消除内耗测最过程中氧吸附的影响．在镀Ｔｉ的Ｔａ—Ｏ试样中详细研究了Ｓｎｏｅｋ—Ｋｏｓｔｅｒ弛豫．观察到了两个内耗峰（较低温度的ＳＫ１峰和较高温度的ＳＫ２峰）．考查之退火温度和氧含量对内耗峰的形状和稳定性的影响．ＳＫ１峰和ＳＫ２峰的激活能分别为１．４和２．１ｅＶ．用Ｓｅｅｇｅｒ的螺位错上的双弯结成核和迁移以及几何弯结的迁移理论解释了实验结果．通过理论和实验比较，得到的螺位错上双弯结形成能约为０．９ｅＶ，螺位错与氧原子的结合能约为０．３ｅＶ实验还发现，进一步冷加工对Ｓｎｏｅｋ峰的影响在实验误差范围内，可以略去不计．     

Ta－O固溶体中的Snoek－K■ster弛豫

试样表面镀一薄层Ｔｉ，消除内耗测最过程中氧吸附的影响．在镀Ｔｉ的Ｔａ—Ｏ试样中详细研究了Ｓｎｏｅｋ—Ｋｏｓｔｅｒ弛豫．观察到了两个内耗峰（较低温度的ＳＫ１峰和较高温度的ＳＫ２峰）．考查之退火温度和氧含量对内耗峰的形状和稳定性的影响．ＳＫ１峰和ＳＫ２峰的激活能分别为１．４和２．１ｅＶ．用Ｓｅｅｇｅｒ的螺位错上的双弯结成核和迁移以及几何弯结的迁移理论解释了实验结果．通过理论和实验比较，得到的螺位错上双弯结形成能约为０．９ｅＶ，螺位错与氧原子的结合能约为０．３ｅＶ实验还发现，进一步冷加工对Ｓｎｏｅｋ峰的影响在实验误差范围内，可以略去不计．     

相变内耗与伪滞弹性

Fe-Ni-C在扩散型(珠光体)相变时呈现较高的内耗峰，说明相界面(尤其是高能相界面)的运动对相变内耗起到重要作用，建议建立一个内耗峰值与相界面能量之间的关系式，Fe-Ni-C中贝氏体相变的内耗特征与珠光体的相似，贝氏体相变孕育期内已发现相变内耗峰．结合溶质区的实验结果，证明贝氏体相变系扩散形核马氏体相变中相界面能量较低，导致其内耗峰值低于扩散型相变的峰值．马氏体相变的软模现象为相变形核机制提供启迪．fcc→hcp反铁磁相变抑制了马氏体相变动力学，但促发了fcc→fct相变，在ZrO2-CeO2一Y2O3陶瓷中，因m→t逆相变而引起的滞弹性可称其为伪滞弹性，其弛豫时间长达数日之久。     

高阻尼镁合金Mg-0.6%Zr和Mg-Ni中内耗峰分析

在高阻尼镁合金研究中,发现了与合金室温下高阻尼性能有关的宽的弛豫内耗峰,该峰为位错内耗峰;该峰是基面位错在热激活作用下运动与点缺陷（空位与溶质原子）相互作用产生。同时在高阻尼合金Mg-Ni和Mg-0.6%Zr中发现了晶界内耗峰。有必要指出的是合金的显微组织会影响晶界弛豫：随着Ni的质量分数增加,晶粒细化同时晶界内耗峰向低温处迁移;同Mg-0.6%Zr合金相比,加入少量的Y后,Mg-0.6%Zr-Y合金晶界弛豫峰向高温处推进。     

INTERNAL FRICTION OF HYDRIDE PRECIPITATION IN Ta-H ALLOYS

测量了冷加工的高纯Ta丝在电解加氢前后的低频内耗。发现在加氢后除出现氢化物沉淀峰外,氢一位错交互作用的内耗峰也降低,附加范性扭形变对沉淀峰有明显的增强作用;在氧原子可动的温度范围内时效,可以完全消除形变对沉淀峰的增强作用。结果表明,氢化物可能择优在位错上沉淀。沉淀峰的本质可能与位错-氢化物交互作用有关。     

Ta中氢化物沉淀过程的内耗研究

测量了冷加工的高纯Ta丝在电解加氢前后的低频内耗。发现在加氢后除出现氢化物沉淀峰外,氢一位错交互作用的内耗峰也降低,附加范性扭形变对沉淀峰有明显的增强作用;在氧原子可动的温度范围内时效,可以完全消除形变对沉淀峰的增强作用。结果表明,氢化物可能择优在位错上沉淀。沉淀峰的本质可能与位错-氢化物交互作用有关。     

Fe－Nb－C合金的高温内耗

测量了高纯Ｆｅ－Ｎｂ－Ｃ合金的４００－８５０℃内耗，发现一个峰温度随测量应变振幅变化的高温（６６６－７４０℃）磁机械滞后阻尼内耗峰。研究了峰的特征、出现、消失条件及升降温、频率、振幅、变形与退火等因素对峰的影响．提出了用内耗实验确定材料中阻碍铁磁畴壁Ｂａｒｋｈａｕｓｅｎ跳动应力的方法和合金中产生磁机械滞后阻尼－温度峰（Ｑ_ｍ~（－１）－Ｔ）的物理机制。     

多孔铜的阻尼性能研究

运用空气加压渗流法制备了直径约1.0 mm、孔隙率高达60%的多孔铜样品,并利用多功能内耗仪对材料的阻尼行为进行了研究。结果表明,多孔铜的阻尼能力比致密铜的阻尼能力有了很大提高,同时在内耗-温度谱上发现有两个内耗峰,分别出现在280℃和400℃左右,激活能分别是1.69 eV和2.30 eV。TEM分析发现基体晶界附近存在大量的位错。经分析认为,低温峰起因于位错与晶界交互作用所引起的对晶界粘性滑移限制,高温峰则由晶界弛豫引起。     

Fe－Nb－C合金的高温内耗SCIEI

测量了高纯Ｆｅ－Ｎｂ－Ｃ合金的４００－８５０℃内耗，发现一个峰温度随测量应变振幅变化的高温（６６６－７４０℃）磁机械滞后阻尼内耗峰。研究了峰的特征、出现、消失条件及升降温、频率、振幅、变形与退火等因素对峰的影响．提出了用内耗实验确定材料中阻碍铁磁畴壁Ｂａｒｋｈａｕｓｅｎ跳动应力的方法和合金中产生磁机械滞后阻尼－温度峰（Ｑ_ｍ^（－１）－Ｔ）的物理机制。     

马氏体相变的分类

马氏体相变按动力学分为变温相变和等温相变。按热力学和界面动态分为热弹性相变、近似热弹性相变和非热弹性相变，其判据为（１）临界相变驱动力小，热滞小；（２）相界面能往复（正、逆）运动；（３）形状应变由弹性协作，马氏体内的弹性储存能对逆相变驱动力作出贡献。按形核机制分为近似局域软模形核和层错形核，前者母相强化阻碍相变开动；后者母相强化不影响Ｍｓ，相变内耗峰出现的温度范围未见模量的明显下降。一级相变特性很     

Compensation effect in grain boundary internal friction

Experimental evidence is provided for the occurrence of the compensation effect, i.e., a linear relationship between the activation enthalpy and the logarithm of the pre-exponential factor, for grain boundary internal friction. The results of internal friction measurements in bicrystals of high purity Al with structurally different grain boundaries were analyzed. The extracted compensation temperature was found to be the same as for grain boundary migration and diffusion of solutes along grain boundaries in Al bicrystals. This temperature divides the investigated temperature range of the internal friction peak into two regimes, with different relations between the magnitude of relaxation time and enthalpy of activation.     

内耗数据的非线性拟合及其在纯铝竹节晶界弛豫中的应用

根据Ｂｅｉｎｇｔｏｎ方法编写了一个可以同时拟合一条的由指数型背影和最多６个弛豫时间具有对数正态分布的内耗峰组成的内耗工曲线的计算机程序,以此方法为基础,定量分析了纯Ａｌ竹节晶界内耗峰的弛豫参数,结果表明,峰温从５３５Ｋ降至４６５Ｋ时,弛豫强度约降低１０％模量弛豫的变化约为４％,弛豫强度随着峰温的降低而有所减少。     

Mechanisms of linear anelasticity in Fe-M and Fe-Al-M (M = Ga, Ge) alloys

Linear anelastic effects in binary and ternary alloys of iron with 13 and 17 at % Ga, 12 at % Ge, and 4–8 at % Al (Fe-13Ga, Fe-17Ga, Fe-12Ge, Fe-8Al-3Ga, Fe-8Al-4Ge, and Fe-4Al-8Ge) have been investigated. In all of these alloys, thermally activated effects of linear anelasticity have been found and identified that are caused by point defects in interstitial (Snoek-type relaxation) and substitutional (Zener relaxation) solid solutions, as well as by dislocations (Hasiguti effect), and by grain boundaries. The effects of the alloy composition on the activation parameters of the above-mentioned relaxation mechanisms have been determined. In addition, frequency-independent effects related to processes of structural rearrangement, such as ordering and disordering of the alloys have been revealed due to the specific features in the curves of the temperature dependences of internal friction for almost all compositions.     

含微量Cu的Fe-P及Fe-P-La合金的晶界内耗SCIEI

本文研究了含微量Cu的Fe-P及Fe-P-La合金系的晶界内耗。发现加进0.584—0.722wt-％的La,明显降低了合金的晶界内耗峰,使晶界峰向高温移动,并在高温处产生一个小内耗峰。对结果做了讨论。进一步阐明了晶界内耗机制:晶界中原子尺寸(即点)缺陷或它们的簇,在应力作用下运动引起内耗。     

Mechanisms of anelasticity in Fe–13Ga alloy

Thermally activated frequency and temperature dependent anelastic effects in Fe–Ga alloys are practically not studied as yet in spite of the capacity of these alloys to dissipate energy of mechanical vibrations due to magneto-mechanical damping. In this paper we have studied iron-based composition with 13 at.% Ga. Several thermally activated peaks have been discovered and their activation parameters are evaluated by means of temperature and frequency dependent internal friction tests using free-decay and forced vibrations. Physical mechanisms are proposed for most of these peaks. In addition to thermally activated relaxation peaks, an irreversible internal friction peak is recorded due to structural transformation around 200 °C. This peak is frequency independent and is accompanied by inverted modulus behaviour. High damping capacity of Fe–13Ga alloy is confirmed.     

Internal friction, dilatometric and calorimetric study of anelasticity in Fe-13 at.% Ga and Fe-8 at.% Al-3 at.% Ga alloys

This paper investigates the structural transitions associated with different cooling rates from a high temperature disordered state and the effect of substitution of Ga atoms by Al atoms in Fe-Ga binary alloys on the ordering processes. Two iron-based low carbon (about 0.04 at.% C) alloys Fe-13 at.% Ga and Fe-8 at.% Al-3 at.% Ga are studied. Internal friction, dilatometric and calorimetric tests are carried out to check ordering in these alloys and contribution of structural defects to relaxation spectrum. Several thermally activated internal friction peaks have been observed and their activation parameters evaluated by means of temperature and frequency dependent internal friction tests using forced vibration. For most of these peaks physical mechanisms are proposed. Apart from these thermally activated relaxation peaks, a structural, frequency independent relaxation takes place at 250-300 °C. Dilatometric and DSC curves show the appearance of a contraction effect in the same temperature range. This effect was studied in alloys cooled down with different cooling rates. We believe that the frequency independent internal friction peak (denoted as the P3 peak in this paper) and peaks at dilatometric and DSC curves are controlled by the same structural mechanism and therefore the activation energy for this anelastic mechanism is derived from DSC data.     

Structure and anelasticity of Fe3Ge alloy

The structure and anelastic properties of Fe-27 at.%Ge alloy are studied. Long-term annealing of the as-cast alloy at 1273 K leads to homogenising and several transformations take place below 873 K. These low temperature transitions are studied by several methods: X-ray diffraction, calorimetry, vibrating-sample magnetometry and internal friction, and are related to magnetic transitions in the different phases. A high stability of the hexagonal (D0₁₉) phase at room temperature is recorded. The hexagonal β (B8₁) phase is also detected in the alloy at room temperature, while the presence of the ′ and phases is doubtful. A broad internal friction relaxation peak with the relaxation strength of Δ = 0.0036, the activation energy of about 1.78 eV and the preexponential relaxation time of τ₀ = 2 × 10⁻¹⁷ s was discovered and classified as the Zener peak in both the and β phases.     

Analysis of the internal friction spectra of high purity aluminium at medium temperatures

The internal friction spectra of high purity aluminium (99.999%) has been thoroughly studied but, at the present time, there is no agreement about the number of peaks at medium temperatures and the number of components of each peak. This paper discusses the reasons for that controversy and summarizes the relaxation processes found in the internal friction spectra. Some authors have assumed that the P₂ peak (also called Kê peak) is formed by two components, one associated to a mechanism of dislocation mobility and the other to grain boundary sliding. However, this assertion is based on weak experimental evidence, which is critically reviewed in this work. The fitting methods used to decompose the internal friction spectra have also been discussed, since some of them can generate spurious components and lead to equivocal conclusions. Another point of great interest that has remained unclear concerns the shifts of the temperature of the peaks observed by many authors, which are explained in this paper with the help of some mechanisms of dislocation mobility. Several specific experimental measurements in 99.999% aluminium and 99.9999% aluminium doped with 10 ppm of copper are presented to clarify these questions. It is concluded that P₂ is composed of just one component and is associated to a mechanism of dislocation mobility. In addition, we have determined that there are only three peaks in the medium temperature range, namely P₁, P₂ and P₃.     

Study of the mechanical properties of TiCN–WC–CO hardmetals by the interpretation of internal friction spectra

TiCN–WC–Mo–Co mixed carbide hardmetals have an interesting application potential for cutting tool fabrication combining the high toughness of WC–Co with the resistance to plastic deformation of TiCN–Co cermets. Mechanical spectroscopy (MS) is used in order to separate the effects of the constituents on the mechanical properties. Internal friction (IF) spectra are measured in a torsion pendulum on WC–TiCN–Mo–Co samples where TiCN/WC ratio is varied as well as the Co content. Six components of the characteristic IF spectrum of WC–TiCN–Mo–Co have been identified and interpreted. Two peaks are located in the cobalt, two peaks in the TiCN phase and two peaks in the ceramic grain boundaries. Four temperature domains are defined depending on the mechanical behaviour: brittle (I), anelastic (IIa), limited plasticity (IIb) and extended plasticity (III). The anelastic domain is characterized by the bulk deformation of cobalt. In the limited plasticity domain, both cobalt and TiCN are deformed by dislocation movement. The high temperature extended plasticity should be attributed to grain boundary sliding in the ceramic phase (mainly WC) enhanced by cobalt diffusion in the grain boundaries.