| 1 | Optimization of N18 Zirconium Alloy for Fuel Cladding of Water Reactors显示文摘In order to optimize the microstructure and composition of N18 zirconium alloy(Zr-1Sn-0.35Nb-0.35Fe-0.1Cr,in mass fraction,%),which was developed in China in 1990s,the effect of microstructure and composition variation on the corrosion resistance of the N18 alloy has been investigated.The autoclave corrosion tests were carried out in super heated steam at 400 ℃/10.3 MPa,in deionized water or lithiated water with 0.01 mol/L LiOH at 360 ℃/18.6 MPa.The exposure time lasted for 300-550 days according to the test temperature.The results show that the microstructure with a fine and uniform distribution of second phase particles(SPPs),and the decrease of Sn content from 1%(in mass fraction,the same as follows) to 0.8% are of benefit to improving the corrosion resistance;It is detrimental to the corrosion resistance if no Cr addition.The addition of Nb content with upper limit(0.35%) is beneficial to improving the corrosion resistance.The addition of Cu less than 0.1% shows no remarkable influence upon the corrosion resistance for N18 alloy.Comparing the corrosion resistance of the optimized N18 with other commercial zirconium alloys,such as Zircaloy-4,ZIRLO,E635 and E110,the former shows superior corrosion resistance in all autoclave testing conditions mentioned above.Although the data of the corrosion resistance as fuel cladding for high burn-up has not been obtained yet,it is believed that the optimized N18 alloy is promising for the candidate of fuel cladding materials as high burn-up fuel assemblies.Based on the theory that the microstructural evolution of oxide layer during corrosion process will affect the corrosion resistance of zirconium alloys,the improvement of corrosion resistance of the N18 alloy by obtaining the microstructure with nano-size and uniform distribution of SPPs,and by decreasing the content of Sn and maintaining the content of Cr is discussed. | B.X. Zhou M. Y. Yao Z.K. Li X.M. Wang J. Zhoua C.S. Long Q. Liu B.F. Luan | 2012 | Journal of Materials Science & Technology2012，28，7： | 13 |
| 2 | An Inverse Approach for Extracting Elastic-plastic Properties of Thin Films from Small Scale Sharp Indentation显示文摘An inverse method for extracting the elastic-plastic properties of metallic thin films from instrumented sharp indentation has been proposed in terms of dimensional analysis and finite element modeling.A wide range of materials with different elastic modulus,yield strength,and strain-hardening exponent were examined.Similar to the Nix-Gao model for the depth dependence of hardness H,(H/H0)2=1+h*Hh,the relationship between elastic modulus E and indentation depth h can be expressed as(E/E0)4=1+h*Eh.By combining these two formulas,we find that there is a relationship between yield stress σ y and indentation depth h:σy = σy0·(1+h*Hh)f(n)·(1+h*Eh)[0.25-0.54f(n)],where σ y0 is the yield strength associated with the strainhardening exponent n,the true hardness H0 and the true elastic modulus E0.f(n)= 1/2(1-n) is constant,which is only related to n,and h*H and h*E are characteristic lengths for hardness and elastic modulus.The results obtained from inverse analysis show that the elastic-plastic properties of thin films can be uniquely extracted from the solution of this relationship when the indentation size effect has to be taken into account. | Z.S. Ma Y.C. Zhou S.G. Long C.S. Lu | 2012 | Journal of Materials Science & Technology2012，28，7： | 4 |
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