Fabrication Of Fine-grain W-Cu With High W Content And Three Layers Gradient Material

Abstract:W-Cu material owns the advantages of both W and Cu, which could be used in the divertor of nuclear fusion reactor and packaging materials in large scale integrated circuit.Researches show that the use of well-distributed fine-grain powder could improve the sintering activity of W-Cu composite.In this paper, an effective process which was spray drying, hydrogen reduction and subsequent ball milling was adopted to fabricate the W/Cu composite material.Then the W/Cu functionally gradient material was manufactured by powder stack, die pressing and liquid phase sintering.This craft could evenly mix the elements of W and Cu in atomic level and could increase the solid solubility of W and Cu. Through the process control, specific composition, powder morphology and sintering characters could be obtained. The experimental results showed that:(1) Flake powder could be got by spray drying-ball milling process.After ball milling, Zigg index decreased obviously,which means the suppression performance of the powder enhanced.After20hours ball milling, particle sizes of W-10/20Cu(wt.%) were1.03and1.15μm, respectively,which need less milling time than the traditional handicraft.(2) Sol-spray drying W-30Cu composite powder were sintered in1380℃for30-120min.The results show the grain growth of W was subjected to the dissolution-precipitation mechanism. Meanwhile, sintering time has more effect on the grain growth than W content.(3) Spray drying W-30Cu could get full density after sintering at1380℃for120min.W-10Cu and W-20Cu could get full density as well under the same sintering process after20hours milling, which also had a uniform composition distribution and fine grain sizes.(4) With emphasis on the relative density and microstructure analysis, the three layers gradient material(3#) was fabricated by20hours milling,powder stacking, pressing and sintering at1380℃for120min. Microstructures showed that fine tungsten grains uniformly distributed in the matrix Cu phase, and the interfaces of gradient materials were clear without obvious defects. Energy spectrum analysis and micro-penetration hardness were explored, which showed the components and the hardness of the gradient material was gradual changed along the gradient direction.