1 INTRODUCTIONSophisticated coating techniques including thechemical vapor deposition, the sputtering, theelectrochemical deposition, and the low pressureplasma deposition of ceramics and metals, can pro duce high quality, thin layered microstructurecomposites that are fully dense. Layer thicknessescan be controlled to a very high degree of microme ter level. However, the production of bulk lami nated composites of any suitable size for practicaluse in structural application by all these processeswould be very expensive. EBPVD technology is akind of evaporating method, taking the electronicbeam as the heat source, making use of high speedmovement of electron to bombard the surface ofthe raw material, then heating it to evaporate, andfinally condensing the vapor on the substrate<1>.Also EBPVD technology has the predominant fea tures like high deposition rate, compact membra nous layer, columnar polycrystalline microstruc ture and high thermal efficiency. Movchen et alhave made use of EBPVD technology to manufac ture thermal barrier coatings and studied theircomposition, structure and properties<2 5>. Ward etal have carried a finite element analysis on themodeling of stress development during the deposi tion of ion assisted coatings<6 9>. Teixeira et al haveconsidered the effects of deposition temperatureand thermal cycling on residual stress state in zir conia based thermal barrier coatings by experi ment<10 12>. Micro layer composites processed byEBPVD usually result in the internal stress forma tion, which can lead to defect the formation anddelamination at the interface of layers<13 16>. So theanalysis of internal stress field in the micro layercomposites during the preparation process is veryimportant. Therefore, in this paper making use ofthe element birth and death technique in the finiteelement(FEM) analysis package ANSYS, the in ternal stress field and the potential displacement changing tendency are numeralically simulated.2 EXPERIMENTALThe micro layer composites prepared by EB PVD technology have many kinds of advantagessuch as low impurity contents, controllable struc ture and crystal grain, homogeneous contextureand constituent. The detailed manufacturing tech nology process is as follows:Firstly, clean up the vacuum evaporatingroom in order to prevent the deposited membra nous layer from contamination. Secondly, deliverthe raw materials to the corresponding position bymechanically driven devices. Thirdly, evacuate theworking room to achieve lower depth of vacuum.Fourthly, preheat the substrate so as to enhancethe cohesion between the membranous layer andthe substrate. Fifthly, deposit a dividing sub layeron the substrate in advance. Sixthly, increase thecurrent strength of electron gun to heat the materi al ingots. Finally, move the gaseous atoms by themanner of straight line and deposite it on the sub strate. The principal scheme of deposition processis shown in Fig.1.Fig.1 Principal scheme of double sourceevaporation by EBPVD1—Rotating substrate; 2—Releasing layer;3—Micro layer composite laminate;4—Electron gun; 5—Ceramic ingot;6—Metal or intermetallic compound ingot;7—Electron gun for preheating substrate;8—Electron gun for heating ingot;9—Observation window3 THEORY BASISVirtually all vacuum deposited coatings are ina state of stress. The total stress is composed of athermal stress and an intrinsic stress. The thermalstress is due to the difference in the thermal expan sion coefficients of the coating and the substratematerials. The intrinsic stress is due to the accu mulating effect of the crystallographic flaws thatare built into the coating during the deposition.These internal stresses in a thin film can give riseto seemingly unrelated behavior that can seriouslyinfluence the performance of film. While the pa rameter T/Tm, where
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