| Flier-plates with graded wave impedance can be regarded as a new kind of functionally graded material (FGM), which has come to show great potential for the application in dynamic high-pressure technology. By using such FGMs, quasi-isentropic loading to target materials can be created.In the present dissertation, the densification mechanisms and the structure controlling of various transient layers of W-Mo-Ti flier-plates with graded wave impedance were mainly investigated. Wholly dense W-Mo-Ti flier-plates were then prepared by powder stacking and hot-pressing. In order to achieve a required wave impedance profile and a quasi-continuous change along the thickness direction, the ratios of components in transient layers were well adjusted. Thus the structure of W-Mo-Ti flier-plates were characteristic of high parallelism and planeness. It is found that, the sintering process of W-Ni-Fe-Cu alloy was a typical liquid-phase process, which including particle rearrangement stage, dissolving-precipitation stage and solid-phase sintering stage. Cu plays an important role in the particle rearrangement stage, while Fe can promote the densification by forming Ni-Fe-W bonding-phase. Ni can not only form the bonding-phase, but also enhance the diffusion between the W grains. In W-Mo alloys with different contents of W and Mo, good coherence between the grains were achieved and they mainly existed as mechanical mixtures. It is also found that the Fe-AI additives were suitable for the sintering of Mo alloy, Ti alloy and Mo-Ti alloys, and they promoted the formation of (p-Ti, Mo) solid solution in Mo-Ti alloys, thus evidently improved relative densities.According to the compositing mode of W-Mo and Mo-Ti system, an ideal mixture model has been suggested to forecast some of related properties for W-Mo-Ti flier-plates. Theoretical formulas described the relations between properties and composition distribution of the flier-plates was also derived. It is shown that, the calculated values were in good accord with that of the testing ones, indicating a high accuracy and reliability.Theoretical model of generating quasi-isentropic compression via flier-plate with graded wave impedance has been established, and study on the numerical simulation was carried out. The results show that, the process of quasi-isentropic compression on target can be seen as the successive overlap of a series of small shock loading waves generated by the transient layers. The design for flier-plates with graded wave impedance should conform to the parabolic or cubic function relationship between the impedance and the thickness. And the thickness of target should also be well designed as for creating a better quasi-isentropic compressive wave profile.Finally, experiments of quasi-isentropic loading to 93W alloys via W-Mo-Ti flier-plates were performed on a two-stage light gas gun. VISAR-measured wave profiles on the free surface of target were profiles with an initial velocity jump followed by a smoothly-rising front to the peak velocity amplitude, showing that quasi-isentropic loading has been successfully generated. The front of the quasi-isentropic wave was obviously extended and the maximum peak pressure value reached 260GPa. It is considered that, the physical process of generating quasi-isentropic compression on target via flier-plates with graded wave impedance can be stated as follows: A series of Hungoniot curves with different original state forms the P-V relation of the target when impacted by a flier-plate with graded wave impedance. This P-V curve can be seen as a quasi-isentropic curve which consisted of isentropic curves. It is found that, the quasi-isentropic curve is located between the Hungoniot curve and isentropic curve, and more close to the latter.
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