The low-cycle fatigue behavior of powder metallurgy Rene95 alloy containing surface inclusions was investigated by in-situ observation with scanning electron microscopy (SEM). The process of fatigue crack initiation a...The low-cycle fatigue behavior of powder metallurgy Rene95 alloy containing surface inclusions was investigated by in-situ observation with scanning electron microscopy (SEM). The process of fatigue crack initiation and early stage of propagation behavior indicates that fatigue crack mainly occurs at the interface between the inclusion and the matrix. The effect of inclusion on the fatigue crack initiation and the early stage of crack growth was very obvious. The fatigue crack growth path in the matrix is similar to the shape of inclusion made on the basis of fatigue fracture image analysis. The empiric relation between the surface and inside crack growth length, near a surface inclusion, can be expressed. Therefore, the fatigue crack growth rate or life of P/M Rene95 alloy including the inclusions can be evaluated on the basis of the measurable surface crack length parameter. In addition, the effect of two inclusions on the fatigue crack initiation behavior was investigated by the in-situ observation with SEM.展开更多
The observation on crack initiation and propagation of surface inclusion Al2O3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix int...The observation on crack initiation and propagation of surface inclusion Al2O3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion / matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion / matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface in-elusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can’t be ignored.展开更多
Nature of PPB precipitation of P/M Rene’95 and its effects on mechanical properties,frac-ture morphology and microfracture characteristics are discussed.Dense PPB precipitatesmake the boundaries brittle and lower the...Nature of PPB precipitation of P/M Rene’95 and its effects on mechanical properties,frac-ture morphology and microfracture characteristics are discussed.Dense PPB precipitatesmake the boundaries brittle and lower the plasticity of the alloy.Fracture path is along theboundaries of particles.As PPB parameter increases,the interfaces between particles arestrengthened.The fracture mode is changed from interparticle to transparticle.As a result,theplasticity at high temperatures and stress rupture life of the alloy are improved.展开更多
基金This work was financially supported by the National Natural Science Foundation of China (No. 50571047) and the National BasicResearch Program of China (No.2004CB619304).
文摘The low-cycle fatigue behavior of powder metallurgy Rene95 alloy containing surface inclusions was investigated by in-situ observation with scanning electron microscopy (SEM). The process of fatigue crack initiation and early stage of propagation behavior indicates that fatigue crack mainly occurs at the interface between the inclusion and the matrix. The effect of inclusion on the fatigue crack initiation and the early stage of crack growth was very obvious. The fatigue crack growth path in the matrix is similar to the shape of inclusion made on the basis of fatigue fracture image analysis. The empiric relation between the surface and inside crack growth length, near a surface inclusion, can be expressed. Therefore, the fatigue crack growth rate or life of P/M Rene95 alloy including the inclusions can be evaluated on the basis of the measurable surface crack length parameter. In addition, the effect of two inclusions on the fatigue crack initiation behavior was investigated by the in-situ observation with SEM.
基金This work was financially supported by the National Nature Science Foundation of China (No.59871007)PM Rene95 materialofferi
文摘The observation on crack initiation and propagation of surface inclusion Al2O3 in seeded PM Rene95 was conducted by SEM in-situ tension test. The results show that the cracks often initiate at the inclusion/matrix interface vertical to the applied stress direction, and easily propagate along the interface into the matrix. The interface of inclusion / matrix is just mechanically bounded on the base of SEM observation. The weak bonding of inclusion / matrix interface and stress concentration around inclusions are the main reasons of the matrix/inclusion interface debonding and local plastic deformation under the tensile loading in the in-situ tension test. Surface in-elusion does not definitely lead to the failure of in-situ tension test. But the early surface crack initiation caused by ceramic inclusion is critically harmful to the LCF property of PM Rene95 superalloy, which can’t be ignored.
文摘Nature of PPB precipitation of P/M Rene’95 and its effects on mechanical properties,frac-ture morphology and microfracture characteristics are discussed.Dense PPB precipitatesmake the boundaries brittle and lower the plasticity of the alloy.Fracture path is along theboundaries of particles.As PPB parameter increases,the interfaces between particles arestrengthened.The fracture mode is changed from interparticle to transparticle.As a result,theplasticity at high temperatures and stress rupture life of the alloy are improved.
