【作者】 王传彬；

【导师】 张联盟； 谭华；

【作者基本信息】 武汉理工大学 ， 材料学， 2003， 博士

【摘要】 波阻抗梯度飞片作为一类新型的功能梯度材料（FGM），因其波阻抗值沿厚度方向呈梯度变化而具有准等熵压缩特性并能进一步用于超高速发射中，可以看作是FGM的优异特性在动高压物理领域中的应用新拓展。 依据实现准等熵压缩和超高速发射对梯度飞片体系的理论要求，论文首先在一个较宽的波阻抗变化范围内，确定钨合金（93W）、无氧铜（OFC）、钛合金（TC₄）、工业纯铝（Al）和镁合金（MB₂）五种综合性能良好的金属和合金材料作为波阻抗梯度飞片的复合体系，并测量了材料的相关声学和力学参量。在此基础上，通过调整飞片中各过渡层材料的厚度，设计了三种波阻抗分布按高幂次（二次、三次）函数关系变化的93W-OFC-TC₄-Al-MB₂系梯度飞片。 利用平面扩散焊接法（控制一定的温度、压力、时间、气氛等条件），同时采取合理的结构控制方法，成功实现了93W-OFC-TC₄-Al-MB₂的整体连接，得到了平面性好、平行精度高、整体致密的波阻抗梯度飞片，满足了设计结果和梯度飞片的基本结构要求。研究表明，93W与OFC的界面连接是OFC与93W中W晶粒的连接以及OFC与93W中Ni-Fe粘接剂的连接共同作用的结果；OFC与TC₄连接界面的形成是由于OFC与TC₄之间发生反应扩散，并由此在二者接头处生成了Cu-Ti金属间化合物的中间相；TC₄-Al的连接与Al-MB₂的连接则分别是其基体元素Ti、Al之间和Al、Mg之间元素互扩散的结果，另外，由于热膨胀系数的差异，扩散焊接后在不同焊件的接头处存在残余热应力并由此引起接头的形变。采取施加外部机械力、控制升降温速率以及尽量降低焊接温度或减少焊接时间（防止脆性金属间化合物的过度增长）等措施，确保了焊接接头的平整性和界面结构的完整性。 建立起梯度飞片击靶的理论模型，对93W-OFC-TC₄-Al-MB₂系波阻抗梯度飞片的击靶过程进行了数值模拟计算。结果表明，梯度飞片击靶后产生的是波阵面明显被展宽的准等熵压缩波，准等熵压缩波的初始速度跳跃、速度峰值和波阵面前沿的上升时间都呈现出不同于传统冲击波陡峭上升波形的特征。随着击靶速度的提高，准等熵压缩波的波阵面前沿的上升时间逐渐减小，而对应的速度峰值和初始速度跳跃则不断增加。靶板厚度必须要与击靶速度相匹配，以保证梯度飞片后界面产生的压缩作用在进入靶板之前，从靶板自由面反射来的稀疏波不会进入飞片中，而当此压缩波在到达靶板自由面之前，武汉理工大学博士学位论文又不会在靶内形成冲击波。 在轻气炮上利用研制的93W-OFC一TC4.AI一MBZ系波阻抗梯度飞片实现了对93W合金（靶材料）的准等嫡压缩，经修正后的测试波形都是由一个较弱的初始速度跳跃和一段呈阶梯状缓慢上升的波阵面前沿所组成的准等嫡压缩波。具有不同梯度结构的飞片，以不同速度撞击不同厚度的靶板时，所得到的准等嫡压缩波波形的变化规律符合数值模拟的结果。波阻抗梯度飞片对靶板的压缩过程是一系列弱冲击加载波相继发生作用叠加的结果，靶板由此获得的尸一v线是一组通过不同初始状态点的Hugoulot线的连线.这条连线可以近似看作是由小段小段等嫡线连接而成的准等嫡线，它位于冲击绝热线和等嫡线之间并更接近于等嫡线。 在二级轻气炮上，利用93W-OFC一TC4一Al一MB:系波阻抗梯度飞片成功将克量级（0.35一2.809）钦合金二级飞片发射到了15kln/s以上的超高速度，且二级飞片主体是完整性，但其平面性和飞行姿态还有待于今后的深入研究。这种超高速发射是波阻抗梯度飞片的无冲击（准等嫡）加速作用和它通过第三级加速器产生的二维能量会聚流动共同作用的结果。更多还原

【Abstract】 Flier-plate with graded wave impedance, which can be regarded as a new type of functionally graded material (FGM) since its wave impedance changes gradually along the thickness direction and thus can be used to generate quasi-isentropic compression energy waves in targets or drive projectiles to hypervelocities, has come to show great potential for the application in dynamic high-pressure technique.In the present dissertation, five commercial metallic materials ?tungsten alloy (93W), oxygen free copper (OFC), titanium alloy (TC-t), pure aluminum (Al) and magnesium alloy (MB2) were chosen as the composite system of the flier-plate with graded wave impedance, and their acoustic and mechanical parameters were measured. The thickness of each material was controlled so that flier-plates with a parabolic or cubic wave impedance distribution were designed.By using diffusion welding method (under certain welding parameters such as temperature, pressure, time and atmosphere, etc) and employing rational structural control technique, a kind of 93W-OFC-TC4-A1-MB2 system flier-plate with good parallelism, planeness and high densification was prepared, which met the needs of initial design and the basic requirement of flier-plates. It was found that the interfacial bonding of 93W-OFC was both the joining action of OFC/W grains and that of OFC/Ni-Fe binders, whereas the joining of OFC to TC4 could be seen as the mutual intense diffusion effect between OFC/TC4 and as a result Cu-Ti intermetallic compounds were formed at the joint. The joining of TC4-A1 and A1-MB2 were also attributed to the result of diffusion between elements Ti-Al and Al-Mg respectively. On the other hand, residual thermal stress and stress-induced distortion were produced at the joint simultaneously due to the difference in thermal expansion coefficient of different welding" materials. The planeness and integrality of the flier-plate were ensured effectively by exerting restrictive pressure, controlling heating and cooling rate, lowering welding temperature or reducing welding time as much as possible, etc.Theoretical model of creating quasi-isentropic compression via 93W-OFC-TC4-A1-MB2 system flier-plate with graded wave impedance wasestablished, and numerical simulation of the impact process was then carried out. The results showed that quasi-isentropic compression energy waves were produced after the impact, whose initial velocity jump, peak velocity and front’s rise-time were all different from the general shock loading wave profiles. Furthermore, the higher the impact velocity, the smaller the extended wave’s front while the higher the peak velocity. At the same time, the thickness of target should also be in accord with the impact velocity.Experiments of quasi-isentropic loading to 93 W alloys by 93W-OFC-TC4-A1-MBz system flier-plate with graded wave impedance were performed on light gas guns. The corrected VISAR-measured wave profiles were profiles with an initial velocity jump followed by a stepwise-rising front to the peak velocity amplitude, indicating that quasi-isentropic compression energy waves had been successfully generated. When flier-plates with different graded structures impacted targets with different thickness at different velocities, the variation of the impact-induced wave profiles accorded with the numerical simulation results. The physical process of quasi-isentropic compression might be considered as the successive overlap of a series of small shock loading waves generated by the transition layers in the flier-plate. As a result, the P-V curve of the target was a quasi-isentropic compression curve, which consisted of small Hugoniot curves (similar to isentropic curves) from different original states, and was located between the Hungoniot curve and isentropic curve but closer to the latter.Finally, on a two-stage light-gas gun, titanium alloy projectiles (with mass of 0.35~2.80g) were driven intact to hypervelocities as over 15km/s by 93W-OFC-TC4-A1-MB2 system flier-plate with graded wave impedance, although the fl更多还原