（ZrNb）2Fe合金相的晶体结构及成分范围

为了研究更低温度下Zr-Nb-Fe三元系中（ZrNb）2Fe相存在的成分范围，熔炼了3个合金样品，其中Fe的含量保持为33．3at．％，Nb的含量分别为5at．％，10at．％和15at．％．经700℃均匀化退火720h后，采用x射线衍射、带能谱的扫描电镜对合金进行物相及成分分析．结果表明700℃时，Nb在（ZrNb）2Fe相中的含量处于5．0at．％-13．79at．％间；文章还给出了（ZrNb）2Fe相的晶体结构数据．     

Fe-C-Cr合金三相共晶与四相包共晶反应对铬系白口铸铁组织的影响

以Fe-C-Cr三元合金相图分析了不同成分的铬系白口铸铁的凝固过程,阐述了三相共晶及四相包共晶反应对其微观组织的影响.通过试验对比,提出了合金元素对铬系白口铸铁微观组织的影响主要是通过对其三相共晶及四相包共晶反应过程的影响而产生.     

Fe-Mn-Si基合金中ε马氏体逆相变的内耗

利用音频内耗仪测试了Ｆｅ－Ｍｎ－Ｓｉ基形状记忆合金热诱发马氏体、一般应力诱发马氏体和热－机械训练后的应力诱发马氏体的逆相变过程．结果表明，热诱发马氏体的逆相变在４００～５００Ｋ完成；经训练后的应力诱发马氏体逆相变开始温度与热诱发马氏体逆相变开始温度相近，但高于一般应力诱发马氏体的逆相变开始温度；一般应力诱发马氏体的逆相变温度低于热马氏体的逆相变温度，随应变量的增加，Ａｓ降低     

Role of β(FeAl) nanoparticles in abnormal grain growth in the annealing of cast Cu-Al-Mn-Fe shape memory alloys

In this study, the low-cost production of Cu-Al-Mn-Fe shape memory alloy single crystals exceeding 46 mm by abnormal grain growth was realized only through annealing their cast alloys. The results show that the misorientation formed during annealing may be responsible for such abnormal grain growth process. It was confirmed that this misorientation resulted from the dissolution of bcc β(FeAl) nanoparticles during heat treatment at a sufficiently temperature of approximately 1173 K. The rate of migration of the abnormal grain boundary was experimentally measured to be approximately 9.3 × 10^-5 m s^-1 within 2 min of the commencement of abnormal grain growth. Additionally, the range of composition of the alloys that can lead to abnormal grain growth was determined. When the Cu-13.0Al-6.5Mn-3.2Fe single crystal close to the [100] direction was deformed to a pre-strain of 12%, full shape recovery happened without any residual strain. At that time, the superelastic strain was approximately 9%. Such a superelastic characteristic remained nearly constant over 50 cycles, showing excellent fatigue resistance. The superelastic properties of the present Cu-13.0Al-6.5Mn-3.2Fe single crystal are compared to those of commercial Ni-Ti-based shape memory alloys. Therefore, it can be considered as a new kind of superelastic material having practical applications. The obtained results should be of great significance in the development of Cu-based shape memory alloys. Furthermore, it is expected that a similar microstructure can be designed for the production of more metallic single crystals.     

Low-frequency damping behavior of closed-cell Mg alloy foams reinforced with SiC particles

The damping properties of an Mg alloy foam and its composite foams were investigated using a dynamic mechanical thermal analyzer. The results show that the loss factors of both the Mg alloy and its composite foams are insensitive to temperature and loading frequency when the temperature is less than a critical temperature T_crit. However, it increases when the temperature exceeds the T_crit values, which are 200 and 250℃ for the Mg alloy foam and the Mg alloy/SiC_p composite foams, respectively. The Mg alloy/SiC_p composite foams exhibit a higher damping capacity than the Mg alloy foam when the temperature is below 200℃. By contrast, the Mg alloy foam exhibits a better damping capacity when the temperature exceeds 250℃. The variation in the damping capacity is attributed to differences in the internal friction sources, such as the characteristics of the matrix material, abundant interfaces, and interfacial slipping caused by SiC particles, as well as to macrodefects in the Mg alloy and its composite foams.     

Effect of alloying elements on magnesium alloy damping capacities at room temperature

Alloying is a good approach to increasing its strength but leads to a reduction of damping to pure magnesium.Classifying the alloying characteristics of various alloying elements in magnesium alloys and their combined effects on the damping and mechanical properties of magnesium alloys is important.In this paper,the properties of the Mg-0.6wt%X binary alloys were analyzed through strength measurements and dynamic mechanical analysis.The effects of foreign atoms on solid-solution strengthening and dislocation damping were studied comprehensively.The effect of solid solubility on damping capacity can be considered from two perspectives:the effect of single solid-solution atoms on the damping capacities of the alloy,and the effect of solubility on the damping capacities of the alloy.The results provide significant information that is useful in developing high-strength,high-damping magnesium alloys.This study will provide scientific guidance regarding the development of new types of damping magnesium alloys.     

Ti--26Nb--4Zr 合金冷轧板材的织构和力学性能

采用 X 射线衍射和室温拉伸方法研究了冷轧变形和固溶处理对 Ti-26Nb-4Zr 合金板材的织构和力学性能的影响.研究发现,50%冷轧时形成了{001}＜uvw＞织构,随着冷变形量的增加,逐渐形成了{121}＜111＞和{001}＜110＞混合织构,＜110＞方向由与轧制方向垂直转到与轧制方向平行.800℃固溶处理后,随着变形量的增加,{111}＜110＞再结晶织构形成并逐渐增强,但＜110＞方向始终保持与轧制方向平行.由于加工硬化及晶粒细化的作用,导致随着变形量增加,冷轧板材的强度逐渐提高,塑性降低.固溶处理后,由于发生再结晶,使得板材的塑性相比冷轧态明显提高.     

铝合金后中值波电流焊接工艺研究

一脉一滴的熔滴过渡被广泛认为是脉冲熔化极惰性气体保护焊中最好的过渡形式,通过在方波脉冲的峰值后增加一个后中值脉冲能有效增强熔滴过渡的可控性,提高焊接过程稳定性和焊缝成形效果.文中利用小波分析仪采集焊接过程瞬时电流电压信号,经过分析得到电流-电压分布概率和U-I图,并将两者与焊缝外观相结合一起综合评定焊接效果.1.2 mm铝合金ER4303焊丝焊接实验表明:在平均电流不变的情况下,采用后中值脉冲波形焊接能明显提高焊缝成形的质量,在焊缝表面形成规整的鱼鳞纹;中值电流取值太小,控制熔滴过渡的作用不明显,只是相当于增加了基值时间;取值太大,相当于增加了峰值时间,焊接过程不稳定;后中值时间太短,能量积累不够,不能控制熔滴过渡;时间太长容易造成熔滴过渡不规则,焊缝的鱼鳞纹消失;后中值电流时间取值在6~10 ms范围内,取值在强弱脉冲电流平均值左右时,焊接过程稳定,焊缝鱼鳞纹光亮、规整、美观.     

Y对Mg-Nd-Zn-Zr铸造镁合金组织和性能的影响

采用光学显微镜、扫描电镜、透射电镜和X线衍射仪等分析研究Y对Mg-Nd-Zn-Zr铸造镁合金组织和性能的影响,并测试其室温力学性能.研究结果表明:Mg-Nd-Zn-Zr-xY(x=0,0.6％,1.2％,1.8％,质量分数)合金铸态组织主要由α-Mg和Mg12(NdaZn1-a)相组成,Y元素主要固溶在α-Mg和Mg12(NdaZn1-a)相中;合金经530℃/14h固溶处理后组织由α-Mg、残余的少量Mg12(NdaZn1-a)相以及方块状Mg24RE5相组成;固溶态合金经200℃/12h时效处理后有大量尺寸为10nm左右的β'和β”析出相生成,能有效地强化基体;随Y质量分数增加,合金室温抗拉强度和屈服强度逐渐上升,最高分别达到271 MPa和161 MPa,较基础Mg-Nd-Zn-Zr合金有较大幅度提高.     

TD3合金离子渗氮耐磨性能研究

采用离子渗氮技术对TD3合金表面进行离子渗氮处理,采用金相显微镜、XRD,对渗氮层的组织形貌、物相结构进行观察分析;用显微硬度仪(维氏)测量渗氮层硬度,再用摩擦磨损试验机(往复式)进行常温干摩擦实验,对其耐磨性、磨痕形貌进行分析。结果表明:渗氮层深度可达80μm,渗氮层显微硬度最高可达1 190 HV,较基材硬度提高2.3倍以上,渗氮层含TiN、Ti_2N。渗氮试样磨痕深度与宽度减小,耐磨性能比基材也有显著提高。