Interface debonding and thermal fatigue life of Ni base alloy composite
Interface debonding is a common feature in Ni base alloy composite.The apparent toughness of composites is much greater than that of either the matrix or the particles.This is attributed to the crack path deflection around.A lot of work has been done to comprehend the role of inclusions on strength,ductility and toughness.This branch of micromechanics has become extremely sophisticated in recent years with extensive computational modeling to unravel nucleation,growth and coalescence of voids around inclusions to explain ductile fracture of engineering alloys.However,there is a need for quantifying the pivotal role played by particles during debonding.To predict the interface debonding of Ni base alloy composite,a suitable mixed-mode interface fracture criterion is required.A special emphasis is given to energetics of in-terfacial arc crack growth to shed more light on the role of elastic mismatch between the ellipsoidal particles and the surrounding matrix.If the thermal expansion coefficients and elastic modulus of Ni base alloy and ceramic particles are different,there will be thermal stresses between particles and matrix in thermosyphon.The thermal stress will arouse the initiation and growth of thermal fatigue crack.First,the three-phase model was used to determine the disturbance strain in two-phases cell aroused by thermal inconsistency.Thinking average stresses in effective matrix vanish,the thermal stress field in Ni base alloy and particles can be gotten.As the interface-crack propagates around the ellipsoidal ceramic particles,the strain energy release rate is examined.When the strain energy release rate reaches the critical value of the matrix,the ultimate debonding stress can be determined.The subtending angle and initiation crack length can be obtained.Finally,based on low-cycle fatigue crack growth rate formation,the thermal fatigue life was computed.The bigger thermal stress is,the smaller thermal fatigue life is.Thermal fatigue life is an exponential function of crack initiation length and critical length.
Interface debonding Thermal fatigue life Ni base alloy Ellipsoidal ceramic particle Composite
Xinhua Ni Xiequan Liu Baohong Han Haixing Lu Guohui Zhong
Department of Basic Course,Mechanical Engineering College,97 Hepingxi Road,Shijiazhuang 050003,China
国际会议
成都
英文
285-290
2009-10-16（万方平台首次上网日期，不代表论文的发表时间）