Al-Ag-Cu-Ti反应扩散连接SiCp/2009Al复合材料的工艺研究

采用Al-Ag-Cu-Ti中间夹层,在真空条件下对SiCp/2009Al复合材料进行了反应扩散连接研究。通过正交试验设计得到了最佳的连接工艺为:连接温度550℃,保温时间60min,压力2×10-3MPa,Ti含量为3wt%。力学性能试验结果表明,采用该工艺得到的接头剪切强度可达120MPa。对连接区进行SEM、XRD和EMPA分析表明,连接区生成了Ag2Al、Al2Cu、Al3Ti、Al3Cu Ti金属间化合物,少量的金属间化合物能起到有效增强接头连接区的作用,和母材的力学性能相匹配,提高连接接头的综合性能。     

SHS-离心复合钢管金属间化合物-陶瓷内衬的显微组织

采用 SHS-离心法制备出金属间化合物 -陶瓷内衬复合钢管。利用扫描电镜、能谱以及 X射线衍射分析方法对内衬组织结构进行了分析。实验结果表明 ,内衬由以 Fe2 Ti、Al2 O3 为主的金属间化合物 -陶瓷层和以 Al2 O3 、Fe O·Al2 O3 为主的陶瓷薄层构成 ,两层之间为冶金结合。其中 Fe2 Ti呈大小不均的颗粒状或团聚状 ,两层中的 Al2 O3 均呈规则块状 ,同时 ,内衬中含一定数量的自蔓延反应不完全产物 Ti3 O5。     

Ti3Al金属间化合物在熔融LiCl-Li2O中的热腐蚀行为

采用浸没法研究了Ti3Al金属间化合物在750℃熔融LiCl-3％Li2O中的热腐蚀行为。结果表明：Ti3Al的耐腐蚀性能优于SS310不镑钢。Ti3Al在腐蚀初期出现了较快的腐蚀,而后腐蚀速率减慢并趋于平缓。Ti3Al经腐蚀后,形成了双层结构的腐蚀膜,外层较厚,由铝的氧化物（LiAlO2,Al2O3）构成;内层较薄,由钛的氧化物（Li2TiQ,TiO2）构成。铝的选择氧化导致了Ti3Al腐蚀初期快速腐蚀,而腐蚀后期腐蚀速率较慢是由于钛的氧化物构成的内层具有较好的保护性。     

镁和钛异种金属冷金属过渡焊接接头微观组织及力学性能的分析

采用冷金属过渡焊接技术,对AZ31B镁合金、工业纯钛TA2异种金属熔钎焊焊接性进行探索研究,从焊接接头的微观组织、元素分布状况研究其连接机理。结果表明:冷金属过渡焊接技术是一种适用于镁、钛异种金属连接的有效方法。通过在过渡区和结合面形成新相可以实现镁、钛的有效连接。焊接接头的焊缝区主要由镁的固溶体?-Mg,骨架状的镁铝金属间化合物Mg17Al12,以及颗粒状分布的Mg17Al(Zn)12组成。镁钛结合面主要靠钛和铝的金属间化合物Ti3Al,以及镁铝金属间化合物Mg17Al12和Mg17Zn12连接。同时,焊接过程中Ti原子以及Al原子的扩散对其结合也有一定的影响。因此,焊接过程中必须保证足够的热输入量,以确保钛母材的熔化及钛、铝原子的扩散,从而提高其结合强度。     

铝合金压铸模堆焊金属粉芯焊丝的研究

根据几类马氏体时效钢的性能和模具堆焊特点 ,确定了铝合金压铸模堆焊金属粉芯焊丝的合金系 ,研究了不同的时效工艺对堆焊层金属硬度的影响机理以及合金元素对堆焊层金属力学性能的影响规律 ,得到最佳时效工艺为 5 0 0℃× 3 h,证明了所研制焊丝堆焊层金属中的强化相是 Ni3 Ti、Ni3(Ti,Al)型金属间化合物。     

热处理条件下激光原位合成高铌Ti-Al金属间化合物复合涂层的微结构特征

为了提高钛合金的高温抗氧化性能,推动钛合金在高温和复杂工况环境下的进一步工程应用,利用高能激光束作用下Ti、Al、Nb三种元素混合粉末之间的原位反应在BT3-1钛合金表面制备了高温抗氧化的高铌Ti-Al金属间化合物复合涂层。针对原位反应所制备涂层存在的缺陷,通过自行设计的热处理工艺优化了涂层和界面微观组织。借助光学显微镜(OM)、X射线衍射仪(XRD)、扫描电镜(SEM)分析了热处理前后复合涂层的物相结构及显微形貌。结果表明:热处理前的涂层主要由单质Nb、金属间化合物γ-TiAl、α_2-Ti_3Al、Ti_3Al_2等物相组成;热处理后的复合涂层,单质Nb固溶到γ-TiAl和α_2-Ti_3Al中,同时形成了新相Ti_3AlNb_(0.3),涂层近似为γ-TiAl+α_2-Ti_3Al双相层片状等轴晶组织。此外,涂层中并未观察到减弱抗氧化性的单质Nb颗粒和Ti_3Al_2相,Ti、Al、Nb的宏观偏析得以消除,涂层与基材界面位置的气孔和裂纹均以消失,出现了明显的白亮带冶金结合过渡层,涂层组织也更加均匀致密。热处理对提高钛合金表面Nb的合金化程度和改善Ti-Al金属间化合物的高温抗氧化性能起到了显著的促进作用。     

搅拌摩擦加工原位合成Al-Ti颗粒增强铝基复合材料的微观结构

采用搅拌摩擦加工法进行了原位合成Al-Ti金属间化合物颗粒增强铝基复合材料的试验,研究了复合材料的微观组织和精细结构。结果表明,以纯Ti粉和纯铝板为原材料,采用搅拌摩擦加工的方法可以原位合成TiAl3金属间化合物颗粒增强铝基复合材料。在复合材料铝基体上,除了生成的TiAl3金属间化合物外,还存在一些纯Ti颗粒以及纯铝基体上的固溶体。经旋转摩擦挤压后,纯铝基体的晶粒得到细化,尺寸为200nm左右,生成的TiAl3晶粒尺寸约为200~300nm。     

Fe_3AL基金属间化合物的性能和应用前景

本文阐述了Fe_3Al金属间化合物的制备和加工工艺、探讨了主要添加元素铈、铬、锰、钼、铌、钨对合金组织及其性能的影响,对室温和高温力学性能、抗氧化性能、耐磨损和腐蚀磨损性能以及电阻率进行了测试和试验,在此基础上探讨了Fe_3Al金属间化合物作为电热元件和耐腐蚀磨损材料的应用.     

Fe—AI金属间化合物材料的制备工艺与研究发展趋势

Fe—Al金属间化合物材料具有很多优秀的性能而被广泛的应用在工程领域中。本文主要讲述Fe-Al金属间化合物材料的制备工艺和性能以及研究发展情况,并对Fe-Al金属间化合物的未来发展趋势进行分析和预测。     

Fe3Al金属间化合物基摩擦材料的制备工艺与性能

采用机械合金化结合加压烧结的方法制备了一种新的Fe2Al金属间化合物基摩擦材料，并对其制备工艺、微观结构和力学性能、抗氧化性以及千滑动摩擦磨损性能进行了试验研究。结果表明：Fe3Al金属间化合物基摩擦材料密度低，强度高，抗氧化性好，摩擦因数稳定，耐磨性好；不同摩擦阶段具有不同的磨损机制，主要包括磨粒磨损、裂纹萌生与扩展、微区脆性剥落以及氧化磨损等。     

Improving of interfacial microstructure of Ti/Al joint during GTA welding by adopting pulsed current

Butt welding of titanium alloy TA15 to aluminum alloy Al2024 dissimilar lightweight metals was conducted using gas tungsten arc welding. Pulsed current was adopted in the welding process. Influence of pulsed current on morphologies and microstructure of Ti-Al intermetallics near the Ti/Al interface was investigated. Microstructure characteristics and phase constitution of weld zone near the Ti/Al interface were analyzed. In top surface and upper region of the joint, Ti base metal was partially melted, and continuous intermetallic layers with Ti₃Al, TiAl, and TiAl₃ were formed in the fusion zone. In middle and bottom regions of the joint, Ti base metal was not melted and a thin TiAl₃ layer was formed near the Ti/Al-brazed interface. Most of the Ti-Al intermetallics formed into discrete TiAl₃ precipitations in the weld metal in upper and middle regions of the joint. No precipitation was observed in bottom region of the joint. Thickness of continuous Ti-Al intermetallic layers in the fusion zone was controlled at a low degree by adopting pulsed current in the welding. Crack sensitivity of weld zone near the Ti/Al interface was decreased.     

Tribochemistry of dry-sliding wear of structural TiAl(Nb,Cr,Zr)B,La intermetallics family against the chromium steel

Effects of microstructure and composition on dry friction, wear and tribochemistry of worn surfaces of new intermetallics Ti–44Al–5Nb–3Cr–1.5Zr, Ti–44Al–5Nb–2Cr–1.5Zr–0.4B–0.07La and Ti–44Al–5Nb–1Cr–1.5Zr–1B–0.17La (at%) sliding against the steel 40Cr have been investigated in air. XRD, SEM, EDX and on-depth ion sputtering techniques were used to investigate the alloys, their worn surfaces and debris particles. For all three alloys the friction coefficient (f) increased vs. sliding way within the range of 0.16–0.39, afterwards followed by the steady state. Neither grain refinement degree, nor content of (Ti,Nb)B, La₂O₃ abrasives in intermetallics affected the stationary f value and wear rate. This tribological behavior reflects the kinetics of FeO-based cover formation on the worn surface, resulting from local oxidation of counterbody steel under the frictional heating-up.     

Ti-48Al-2Cr-2Nb钛铝化合物的韧化和氧化抗力研究

在ＴｉＡｌ合金中添加过渡族合金元素，观测了其微观组织和结构，测定了室温弯曲性能和高温氧化性能，研究了改善塑性及提高其高温氧化抗力的因素。试验结果表明，与单相γ－ＴｉＡｌ不同，添加过渡族元素Ｃｒ、Ｎｂ的Ｔｉ－４８Ａｌ－２Ｃｒ－２Ｎｂ钛铝化合物所形成的双相或等轴γ和α２／γ片层状双态组织，改善了脆性γ－ＴｉＡｌ合金的室温塑性，使弯曲强度达４９０ＭＰａ，弯曲挠度为０．３９ｍｍ；；大量层错带和变形孪晶的形成是室温变形的主要机制。另外，在高温下，钛铝化合物的表面由表及里形成了不易剥落的ＴｉＯ２、Ａｌ２Ｏ３及ＴｉＯ２＋Ａｌ２Ｏ３三层氧化层，连续、致密的Ａｌ２Ｏ３层是提高氧化抗力的重要原因     

PCBN刀具高速切削钛合金切削力和表面质量的研究

针对PCBN刀具材料和钛合金Ti6Al4V工件材料的特点,采用单因素试验法,对切削力和已加工表面粗糙度进行研究。通过与其它刀具材料作对比,证明了PCBN在高速、低进给量、低背吃刀量下切削钛合金可以得到较平稳的切削力和较低的工件已加工表面粗糙度。     

Sliding wear performance of reinforced A413 alloy at elevated temperatures

Dry sliding wear behaviour of Al–Si A413 alloy with and without intermetallics has been studied at ambient and elevated temperatures. It is observed that as the temperature is increased, the wear rate decreased. The reduction in wear rate is mainly attributed to the formation of glazing layers at elevated temperature and is observed in both A413 alloy with and without intermetallics. The wear due to oxidation is predominant during high temperature sliding.     

Fretting wear of mechanically alloyed AlFe and AlFeMn alloys

A double mechanical alloying process (dMA) was employed to fabricate AlFe and AlFeMn alloys containing finely distributed intermetallic compounds and inert dispersoids (Al₄C₃ and Al₂O₃). The tribological properties of the produced alloys were investigated under fretting conditions. It was shown that the fretting behaviour strongly depends on contact conditions which are mainly determined by displacement and normal load, and the wear resistance of Al alloys can be improved by dispersion of large amount of intermetallics and inert dispersoids. Compared with current and competitive wear resistant Al alloys, the dMA AlFeMn alloy shows attractive wear and friction properties. The results indicate that Al alloys fabricated by dMA are promising for wear-resistance applications.     

Al_2O_3Cu-Ti-Zr/Nb钎焊研究

使用Cu Ti Zr钎料对Al2 O3 Nb进行了钎焊试验。通过扫描电镜、能谱、X射线衍射分析了界面形貌、元素分布 ,并对反应相进行了判定。Cu70 Ti2 5 Zr5 钎料在 12 93K、10min条件下界面产生了 3种新相 :Cu2 Ti4O、Ti固溶体、CuTi,界面结构为Al2 O3 Cu2 Ti4O Ti固溶体 CuTi Cu固溶体 +CuTi。采用拉剪试验评定了强度 ,结果证实12 93K、10min ,使用Cu70 Ti2 5 Zr5 钎料的接头强度最高达到 16 2MPa ,增加或减少Ti的质量分数以及改变保温时间都会使接头抗剪强度下降。     

反应生成Al3Ti、Al2O3/Al复合材料的力学性能研究

讨论了不同的TiO2/Al摩尔比对Al-TiO2系热扩散反应法（XD）合成铝基复合材料的力学性能的影响。反应产物Al3Ti呈棒状，Al2O3呈细小颗粒状；随着TiO2/Al摩尔比的增加，增强相（Al3Ti、Al2O3）体积分数提高，材料的拉伸强度明显增强，伸长率逐渐减小。棒状物Al3Ti强底低，阻碍Al3Ti、Al2O3／Al的拉伸性能进一步提高。     

Microstructure and joining mechanism of Ti/Al dissimilar joint by pulsed gas metal arc welding

Butt joining of titanium alloy Ti–2Al–Mn to aluminum 1060 using AlSi5 filler wire was conducted using pulsed gas metal arc welding. Joining mechanism of Ti–2Al–Mn/Al 1060 dissimilar joint with different welding heat input was investigated. Formations of precipitation and Ti/Al interface were discussed in detail. Fusion zone near aluminum is composed of α-Al dendrites and Al–Si hypoeutectic structures. A few TiAl₃ precipitations appear in the weld metal owing to metallurgical reactions of Al with dissolved Ti. When the welding heat input was in the range of 1.87–2.10 kJ/cm, titanium alloy Ti–2Al–Mn and Al 1060 were joined together by the formation of a complex Ti/Al interface. With a low welding heat input, a serrate TiAl₃ interfacial reaction layer was formed near Ti/Al interface. With the increasing of the welding heat input, α-Ti, Ti₇Al₅Si₁₂, and TiAl₃ layers were formed orderly from Ti–2Al–Mn to weld metal.