Effect of Film Elastic Modulus on Fatigue Behaviour of DLC-Coated Wrought Magnesium Alloy AZ61
Effect of Film Elastic Modulus on Fatigue Behaviour of DLC-Coated Wrought Magnesium Alloy AZ61
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DOI：
10.1016/j.proeng.2011.04.179
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发表时间：
2011
期刊：
影响因子：
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通讯作者：
T. Kakiuchi;Y. Uematsu;T. Teratani;Y. Harada
中科院分区：
文献类型：
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作者：
T. Kakiuchi;Y. Uematsu;T. Teratani;Y. Harada
为研究膜弹性模量对AZ61镁合金疲劳性能的影响，采用两种不同膜弹性模量的dlc涂层进行了平面弯曲疲劳试验。采用DLC膜提高疲劳强度，其中弹性模量较大的DLC膜提高疲劳强度效果更好。在裂纹起始点附近观察到母材DLC膜的分层现象。薄膜弹性模量越大，小裂纹和分层的数量越多。与没有DLC膜的母材相比，DLC膜使母材与DLC膜边界附近的应力在试样中得到了重新分布。由于母材与DLC膜的弹性模量不同，母材处应力减小，而DLC膜处应力较大。采用有限元法计算了母材和DLC膜边界附近的应力。有限元分析表明，基底金属处应力减小，DLC膜处应力增大，基底金属与DLC膜处应力差随着膜弹性模量的增大而增大。认为DLC膜对母材滑移变形的牢固抑制能有效提高疲劳强度，且DLC膜内的大应力不会对疲劳强度产生负面影响。
Plane bending fatigue tests were conducted using DLC-coated magnesium alloy AZ61 with two different film elastic moduli in order to investigate the effect of film elastic modulus on fatigue behaviour. Fatigue strength was improved by DLC film where DLC film with larger elastic modulus was more effective to improve fatigue strength. Delaminations of DLC film from base metal were observed near crack initiation sites. The number of small cracks and delaminations was larger as film elastic moduluswas larger. By DLC film, stress near the boundary between base metal and DLC film is redistributed in a specimen compared with parent material without DLC film. Stress is reduced at base metal but large stress occurs at DLC film due to the differenceof elastic moduli of base metal and DLC film. Stress at base metal and DLC film near the boundary is calculated by FEM (Finite Element Method) analysis. FEM analysis showed that stress decreases at base metal, stress increases at DLC film and that the difference of stresses at base metal and DLC film becomes larger when film elastic modulus is larger. It is considered that firmrestraint of slip deformation in base metal by DLC film is effective to improve fatigue strength and that large stress in DLC film would not give negative effect on fatigue strength.