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hour219

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noel1999e

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hour219: 金币+5, 翻译EPI+1, ★★★★★最佳答案 2013-05-26 08:47:15
(2)The initial hot rolling compound diffusion temperature and time were 800 ℃ and 1h , respectively . this condition can ensure valid connection between Pt and Ti, with less  intermetallic compound formed at the interface (α-Ti + Ti3Pt). 90% deformation will inevitably lead to non-uniform deformation in Pt / Ti composite blanks with varying thickness in each metal layer , particularly in Ti layer thickness , and the thinner Ti layer in some places breakage is noted while Pt layer remains intact. At a higher temperature (700 ℃) annealing, a greater annealing frequency is associated with a layered structure more continuous and complete, while at lower temperatures (500 ℃) annealing, increasing the annealing frequency will obtain a layered structure not qualified as that obtained with a lower annealing frequency . For samples processed by intermediate isothermal annealing, the layered structure is better than that obtained without direct rolling annealing with annealing deformation up to 50%, and the best uniformity and continuity in a sample layer like structure was observed when the annealing temperature was set at  500 ℃.  Compared with the Hot pressing diffusion, samples obtained with rolling composite approach have an relatively minor diffusion, with deformation in repeated annealing samples up to 90% , but the diffusion of Pt and Ti elements is still confined to the portions around the interface without further diffusion into the substrate of the other part. The intermetallic compounds obtained by annealing at 700 ℃ are all α-Ti + Ti3Pt while those obtained at 500 ℃ are all Ti3Pt. Compared with cold rolling, the Ti layer in composite blanks obtained with warm rolling also have fracture phenomena  present . As the deformation increases, the central part of the layered structure remains relatively uniform and complete with evident rolling deformation, however, the layered structure in both sides has less uniform thickness than that in the central part ; warm rolling process does not generate the intermetallic compound, or generate only a small amount of discontinuity intermetallic compounds which is very difficult to observe .

(3) The mechanical properties and fracture results of rolling samples . Annealing deformation (30% or 50%) has little effect on the sample interface hardness, i.e., the difference between 500 ℃ annealing and 700 ℃ is less than 10HV; but the temperature has a more significant effect on the interface hardness, i.e., the interface hardness of 700 ℃ annealed sample is 100HV higher than that of 500 ℃ annealed sample; and interface hardness of the warm rolling sample was only 103.6HV. 50% / 500 ℃ annealed samples have the best tensile performance, which can withstand the maximum load of 297.451N, maximum stress of 576.455N/mm2, and the strength is second only to the 50% / 700 ℃ annealed samples, but it’s ductility is far better than that of other samples, thus , has the best overall performance. Not annealed Pt / Ti composite material fracture is composed of two phases, the intermetallic compound layer in the interface fractures in a brittle fracture mode, then ,the Pt and Ti metal layer subsequent fractures in a ductile fracture mode, the fracture in sample processed by annealing is more uniform and the fracture process is more in coordination.
2楼2013-05-25 16:40:57
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