W骨架/Zr基非晶合金复合材料破片冲击释能特性研究

采用准密封箱冲击超压实验,研究了W骨架/Zr基非晶合金复合材料的在不同冲击速度下和靶板厚度下的冲击释能特性。并根据温度控制含能结构材料冲击诱发化学反应的热动力学理论,拟合了材料反应的表观活化能E_a和反应系数n,分析了材料的热化学反应特性。结果表明,材料冲击超压峰值与冲击速度正相关,其激发反应阈值为766m/左右,在相同速度下,有使破片靶后释能效率最大化的最优靶板厚度,但在8mm厚钢靶范围内,前板厚度对冲击释能特性影响不大。材料冲击激发化学反应的冲击压力阈值P_c=18.37GPa,对应的理论温度阈值T_c=3736.6K。材料反应效率随着冲击压力和击波温度的增加而增加,在40GPa冲击压力范围内,材料并未完全反应,其理论反应效率达到61.5%。     

Ni-Al含能结构材料的制备和性能研究

以Ni粉和Al粉(摩尔比1:1)为原料,采用冷压-烧结法制备了Ni-Al含能结构材料。研究了烧结温度对Ni-Al含能结构材料界面扩散、力学性能、起始反应温度和能量密度等的影响。结果表明：烧结温度的提高,增加了Ni-Al颗粒间界面扩散速率,从而使含能结构材料界面粘合强度增大,拉伸和压缩强度提高,同时,能量密度降低;当烧结温度为550℃时,可获得强度和能量密度俱佳的含能结构材料,其拉伸和压缩强度分别为66.0 MPa和294.6 MPa,能量密度为436.1 J/g。     

Ni-Al含能结构材料的制备和性能

以Ni粉和Al粉(摩尔比1:1)为原料,采用冷压-烧结法制备了Ni-Al含能结构材料。研究了烧结温度对Ni-Al含能结构材料界面扩散、力学性能、起始反应温度和能量密度等的影响。结果表明:烧结温度的提高,增加了Ni-Al颗粒间界面扩散速率,从而使含能结构材料界面粘合强度增大,抗拉强度和压缩强度提高,同时,能量密度降低;当烧结温度为550℃时,可获得强度和能量密度俱佳的含能结构材料,其抗拉强度和压缩强度分别为66.0 MPa和294.6MPa,能量密度为436.1 J/g。     

喷丸辅助对冷喷涂Ni-Al含能结构涂层组织及性能的影响

目的 调控冷喷涂Ni-Al含能结构涂层的微观结构,增加涂层中组元间的接触面积,提高涂层反应速度。方法 在Ni、Al混合粉末中引入铸钢弹丸,研究喷丸辅助对冷喷涂Ni-Al涂层微观组织、力学性能和反应特征的影响。采用扫描电镜(SEM)结合定量金相方法,表征Ni-Al涂层微观形貌和Ni、Al组元的接触面积。通过万能材料试验机及分离式霍普金斯压杆(SHPB)测试Ni-Al涂层的压缩力学性能。采用差示扫描量热分析法(DSC)分析Ni-Al涂层的反应温度及放热量。通过高速摄影分析Ni-Al涂层的自蔓延反应过程和燃烧速度。结果 喷丸辅助冷喷涂所制备的Ni-Al涂层整体致密、无宏观裂纹。弹丸冲击提高了涂层中Ni颗粒的变形程度和Ni、Al组元间的接触面积,对涂层密度和Ni、Al活性组元含量无明显影响。喷丸辅助冷喷涂Ni-Al在准静态和动态条件下的抗压强度分别为210~250 MPa及310~335 MPa。引入弹丸提高了冷喷涂Ni-Al涂层的反应活性,反应起始温度下降至422 ℃,并显著提高了冷喷涂Ni-Al含能结构涂层的自蔓延燃烧速度。当钢丸添加量为77%时,涂层燃烧速度达到416 mm/s,提高近5倍。结论 喷丸辅助冷喷涂工艺可在保证涂层力学性能的同时,提高Ni-Al含能结构涂层的反应活性,并显著提高自蔓延燃烧速度,弹丸含量对涂层成分影响不大。     

热压合成铁基表面涂层的微观结构研究

采用真空热压法制备出铁基表面Ni3Al涂层、TiC/Ni3Al涂层及TiC/Ni3Al-Ni3Al双层涂层,研究了不同涂层的微观结构及相组成,并用洛氏硬度计对涂层剖面进行了硬度测试。结果表明:TiC/Ni3Al-Ni3Al双层涂层结合了Ni3Al涂层、TiC/Ni3Al涂层两者的优点。表层涂层的微观组织为TiC颗粒较为均匀的分布在Ni3Al基体上,组织纯净、致密,过渡层Ni3Al相与表层涂层及钢基体之间均为良好的冶金结合。TiC/Ni3Al-Ni3Al双层涂层既维持了TiC/Ni3Al涂层的高硬度,又实现了从表层至基体之间性能的梯度过度。     

分段结构的钨丝/锆基非晶复合材料弹芯穿甲实验研究

为了研究不同结构和材料弹芯的侵彻能力,采用80%体积分数的钨丝/锆基非晶复合材料(钨丝直径0.3 mm)弹芯,在1450~2100 m/s速度范围内,对不同结构方案的弹芯垂直侵彻均质靶板进行了实验研究。结果表明:(1)材料的性能和结构都可以影响弹丸的侵彻效率,突破了传统认识,为复合材料杆式穿甲弹设计提供了重要依据;(2)弹芯结构不同,其侵彻深度-着靶速度变化曲线也不同,对于两段和三段结构弹芯其侵彻曲线变化是凸的,其侵彻深度峰值分别出现在着靶速度1750~1800 m/s和1850 m/s附近,最大侵彻穿深均为x=1.7L;对于未分段弹芯,其侵彻深度-速度变化曲线呈渐近线变化,在速度大于1850 m/s时接近于流体动力学极限穿甲深度L·(ρ/2p/ρt)~(1/2),约为1.5L;(3)结合单向纤维复合材料的动态破坏特点、动态裂纹传播和弹芯高速撞击的侵蚀速度特性,给出了最优分段概念,分析了(2)中发现的问题的原因,为分段弹芯结构设计提供了参考。     

Zr基非晶合金反应材料的力学性能与冲击烧蚀特性

为了提高锆基非晶合金反应材料冲击反应产生的烧蚀毁伤效能，用热电偶测量非晶破片撞击准静态腔室后容器内温度场的变化，研究元素组分对破片冲击反应烧蚀特性的影响。而且力学性能对于其侵彻能力和释能能力起重要作用，为分析钛和铌对反应材料力学性能的影响，开展了锆基非晶合金的准静态压缩试验和SHPB杆动态压缩测试。试验结果表明：钛能为非晶破片提供较大的塑性变形能力，铌能提升非晶破片的弹性模量，随着加载应变率增加，两种材料的脆性增加而塑性降低；温差峰值可以相对表征非晶破片的烧蚀效能；在相同条件下，锆钛基破片对目标的烧蚀作用优于锆铌基破片。     

Si3N4/Ni/TiAl扩散连接接头界面结构及性能

采用厚度为80 μm的镍中间层实现了Si3N4陶瓷和TiAl合金的扩散连接.采用扫描电镜(SEM),能谱检测(EDS)等分析方法确定了TiAl/Ni/Si3N4扩散焊接头的典型界面结构为TiAl/Al5Ni2Ti3/AlNi2Ti/Ni3(Ti,Al)/Ni(s,s)+Ni3Si/Si3N4.重点分析了连接温度对接头界...     

反应热压制备TiC/Al复合材料的形成途径研究

利用场激发反应热压合成技术研究了Al-Ti-C混合粉末体系制备TiC/Al产物的过程与致密性,并结合DSC实验分析了该体系合成TiC相的形成途径。结果表明,采用反应热压合成法完全能够制备较致密的TiC/Al复合材料。该体系形成TiC相的反应过程为:Ti(s)+3Al(s)=TiAl3(s)→Al(s)=Al(l)→Ti(s)+3Al(l)=TiAl3(s)→TiAl3(s)=TiAl3(l)→TiAl3(l)+C(s)=TiC(s)+Al(l)。混合粉末中的Al不仅作为稀释剂降低体系的反应温度而细化TiC晶粒,还作为反应剂参与了整个反应进程。     

NiAl合金变截面管件热态气压成形-反应制备复合工艺

NiAl金属间化合物具有较高的高温强度且密度低于传统镍基高温合金，针对NiAl合金变截面薄壁构件制造难题，开展了Ni/Al叠层材料变截面管件热态气压成形-NiAl合金反应制备的复合成形工艺研究。首先，通过Ni/Al界面调控，制备出层间结合紧密且塑性高的Ni/Al叠层圆筒坯；然后，在不同工艺参数下研究了Ni/Al叠层材料的热态气压成形规律及微观损伤控制方法，成形出贴模良好的变截面管件；最后，通过反应制备将Ni/Al叠层材料构件转变为NiAl合金构件。研究表明：温度和气压加载速率是Ni/Al叠层材料热态气压成形的关键参数，在合理的温度下，通过气压加载速率调控应变速率，可避免微观损伤、控制圆角精度；经反应制备获得的NiAl合金变截面薄壁构件，其900℃时的抗拉强度达到110 MPa。     

热压烧结制备Al2O3/TiCN-Ni-Ti陶瓷复合材料的组织与性能

采用真空热压烧结方法制备Al2O3/Ti(C,N)-Ni-Ti陶瓷基复合材料,采用X射线衍射与扫描电镜分析材料的物相组成和显微结构,研究烧结工艺对材料物相组成、显微结构和力学性能的影响。结果表明:Ni和Ti的添加显著提高复合材料的强度和韧性;温度小于1 600℃时,复合材料的力学性能随热压温度的升高而升高;温度高于1 600℃时,温度升高及保温时间延长不仅会导致Al2O3晶粒的异常长大和Ti(C,N)的分解,而且会使Ni发生聚集现象,复合材料的力学性能下降;当烧结温度为1 600℃、保温时间为30 min时,制备的Al2O3/Ti(C,N)-Ni-Ti陶瓷复合材料的力学性能最佳,其相对密度达到99.4%,抗弯强度为820 MPa,断裂韧性达到9.3 MPa.m1/2。     

Nb-Cr掺杂原位合成Al2O3/TiAl复合材料的组织与性能

采用原位热压工艺,在Ti-Al-TiO2-Nb2O5体系中加入Cr2O3原位合成Al2O3/TiAl复合材料.借助X射线衍射分析、SEM分析及力学性能分析,研究了Nb-Cr掺杂复合强化Al2O3/TiAl复合材料的反应过程、微观结构及力学性能.结果表明Nb-Cr掺杂原位合成Al2O3/TiAl复合材料能够细化晶粒并通过微合金化增强增韧TiAl复合材料.     

Fabrication of Ni3AI by hot pressing from element powders

Ni3Al intermetaUic was synthesized by hot pressing from element powders of nickel, aluminum, and boron. The influences of parameters on the properties of Ni3Al were investigated. The parameters include the particle size of nickel powder, adding or without boron powder, hot pressing temperature, etc. The properties include the density of hot-pressed samples, resultant redo of Ni3A1 phase, and bending strength. The microstructures of hot-pressed samples were investigated by X-ray diffraction and scan electronic microscopy, and the properties, such as density and bending strength, were also measured. The results show that a higher bending strength was obtained under the same hot pressing conditions by the fine nickel powder than the coarse one, and there is little difference about density. Boron powder added in this process accelerates the formation of Ni3Al and markedly increases the hot pressed density. In the temperature range of this study, the density increases along with the hot pressing temperature. Full dense Ni3Al samples were obtained under the condition of 860℃, 10 min, 45 MPa from Ni-22.89A1-0.5B powder.     

Effects of sintering temperature and Ni/Fe ratio on ballistic performance of tungsten heavy alloy fragments

The aim of this study was to investigate the effects of the sintering temperature and Ni/Fe ratio on the ballistic performance of liquid-phase sintered tungsten heavy alloys. The powder mixtures were pressed under 300 MPa and sintered at 1460, 1480, and 1500 °C for approximately 30 min in a reducing and protective atmosphere. Ballistic tests were performed by accelerating tungsten heavy alloy fragments with a velocity of ~900 m/s toward a 25 mm-thick Al 6061-T6 target. Simulation studies were performed using the finite-element method to model the deformation of the fragment and the target. The experimental results showed that the highest residual velocity and the best perforation performance for multiple-layered targets were obtained with a 93 W-4.67Ni-2.33Fe alloy sintered at 1480 °C, and the increase in the sintering temperature and plastic deformation of the fragments enhanced the damage on the target during the impact process via hole enlargement on the target. The simulation results showed that the mesh sizes of the fragment and the target affected the modeling of the fragment/target deformation and the residual velocity of the fragment. Additionally, the simulation results showed good correlation with test results with regard to the modeling of the deformation at the impact and rear surfaces of the target during perforation.     

Energetic intermetallic materials formed by cold spray

Cold spray was used to synthesize three intermetallic energetic materials from powders composed of mixed Ni/Al, mixed Ni/Al/MoO₃, and Ni-clad Al. After bulk samples were produced, characterization was performed to determine their composition and reactivity. Ignition was achieved with a 30 W CO₂ laser and propagation rates were measured using a high speed digital video camera. Differential scanning calorimetry was used to obtain energetic properties of the composites at slow heating rates. The energetic properties of cold sprayed samples were compared with lower density axially pressed pellets of identical composition. Samples composed of a mechanical blend of Ni and Al powders had higher reaction propagation rates at lower densities; with the near fully-dense cold spray samples having the lowest propagation rates. The opposite was found in samples composed of Ni-clad Al powders, with propagation rate increasing with increasing density for pellets, and reaching a maximum in the cold sprayed samples. The samples containing MoO₃ had mixed results, with pellets experiencing higher propagation rates for all MoO₃ contents' with increasing density, but cold sprayed samples having lower propagation rates as the MoO₃ content increased.     

Cr3C2/Ni3Al复合材料的微观组织和室温耐磨性

采用药芯焊丝法制得Ni-Al-Cr3C2复合焊丝,将该焊丝堆焊于工件表面,在堆焊过程中,利用氩弧物理热和Ni-Al反应热,Ni与Al化合反应生成Ni3Al金属间化合物,Cr3C2则发生分解,除少部分[C]与[Cr]固溶于Ni3Al基体中外,大部分反应重新析出细小的Cr3C2相,均匀地分布于Ni3Al基体中.室温磨粒磨损和微动磨损实验结果表明,Cr3C2/Ni3Al复合材料的耐磨性为Stellite12合金的2倍左右,较高的硬度、高的碳化物体积分数以及碳化物与Ni3Al基体间良好的界面结合力是Cr3C2/Ni3Al复合材料耐磨性优良的主要原因.     

碳化硅纤维增强体钛铝基体的原位合成与控制及其动力学解析

利用磁控溅射,采用钛靶和铝靶按照一定功率比在SiC纤维表面沉积钛与铝,制备SiC纤维的Ti-Al基复合先驱丝,按密排堆垛置于包套之中并经热等静压制备碳化硅纤维增强钛铝基试样。通过扫描电镜观察组织形貌,研究热等静压及真空热处理对组织结构、界面反应层的影响,应用XRD与能谱分析,研究磁控溅射功率对原子比的影响以及钛铝原位反应过程中相比例的变化规律,采用差示扫描量热法(DSC,differential scanning calorimetry)对钛铝反应进行动力学分析。结果表明,钛靶与铝靶的溅射功率直接影响钛铝的原子比,TC4和Al靶功率分别为13和4.5 kW/m2,其铝含量为27at%;TC4和Al靶功率分别为13和8.3 kW/m2,其铝含量为49at%。此外,动力学研究表明,Al3Ti是钛铝反应的优先生成相,随着Al的扩散,逐渐形成TiAl、Al2Ti和Ti3Al,但经过Al的充分扩散,其最终形成的稳定相取决于钛铝的原子比,若原子比为1:1,则最终形成TiAl相,且不同原子比区域形成的TiAl、Ti3Al可共存。     

ELECTROCHEMICAL IMPEDANCE OF HOT CORROSION OF SPUTTERED CoCrAlY COATING ON Ni_3Al And Ni_3Al－Fe INTERMETALLICS

采用电化学交流阻抗技术并结合物相分析技术研究了溅射ＣｏＣｒＡｌＹ涂层对Ｎｉ３Ａｌ、Ｎｉ３Ａｌ－Ｆｅ金属间化合物在７００℃熔融（Ｎａ，Ｌｉ，Ｋ）２ＳＯ４中腐蚀行为的影响．结果表明，Ｎｉ３Ａｌ和Ｎｉ３Ａｌ－Ｆｅ的耐熔融盐腐蚀性能较差，其交流阻抗Ｎｙｑｕｉｓｔ图高频端表现为一曲率半径很小的圆弧，低频端为一直线，腐蚀反应受氧化剂的扩散所控制；施加ＣｏＣｒＡｌＹ涂层后，Ｎｙｑｕｉｓｔ图则呈双容抗特征，发生了沿涂层缺陷的腐蚀；提出了交流阻抗模型并解析了其中的参数．     

Welding of Ti–6Al–4V and TiB2–Ni cermet using pulsed current heating

Abstract

Ti–6Al–4V alloy was joined with TiB₂–Ni cermet by using pulsed current heating and hot pressing. The properties were found to be better with the pulsed current process, because the current enhanced the growth of Ni–Ti phase at the junction between the two materials. Furthermore, the heat affected zone is localised in the pulsed current process relative to that in the hot pressed material.