Investigation of Effect Mechanism of Hafnium and Zirconium in High Temperature Materials

ZHENG Yun-rong; CAI Yu-lin; RUAN Zhong-ci; MA Shu-wei

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Journal of Aeronautical Materials ›› 2006, Vol. 26 ›› Issue (3) : 25-34.

Investigation of Effect Mechanism of Hafnium and Zirconium in High Temperature Materials

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Abstract

Hafnium and zirconium can promote the formation of (γ+γ′) eutectic,MC(2) carbides,M2SC sulfides and Ni5M phases in superalloys,change script MC and M3B2 into blocky shape and delay the initiation and propagation of cracks by cleaning the free state sulfur at grain boundary and interdendritic regions and strengthening their cohesion.Both of elements Hf and Zr increase the stress rupture strength and ductility of cast superalloys at intermediate temperature and also improve the tensile strength and ductility at room temperature.Hf and Zr strict the precipitation of secondary carbides,such as M23C6 and M6C,therefore stabilize the microstructure of alloys during long-term exposure at elevated temperature.However,Hf and Zr lower the incipient melting temperature of superalloys.The melting of Ni5Hf or Ni5Zr phases may be considered as one of the main factors affecting incipient melting.By means of a pretreatment at 1150℃/8h,Ni5Hf phase can be eliminated in two ways: The reaction Ni5Hf+ γ(C) →MC(2)+ γ or solid solution.Hafnium may narrow down the range between temperature lost the interdendritic capillary feeding action and solidus,as well as may decrease the liquid content necessary for linking the interdendritic pools in the late solidification.The Hf-rich melts in interdendritic zone have superior fluidity,wettability and skin effect.These are the factors in increasing castability and weldability of Hf-containing superalloys and in decreasing tendency of hot tear.The high chemical activity of skin Hf-rich liquid promotes the formation of a thin layer of Hf2O on the surface of castings.Hf and Zr are the melting point depressant in the interlayer alloys used for brazing.It may be considered that dendrites formed in the early solidification are brazed by interdendritic Hfor Zr-rich melts.Eventually,the Ni-18.6Co-4.5Cr-4.7W-25.6Hf and Ni-10Co-8Cr-4W-13Zr alloys were developed according to the composition of Hf-or Zr-rich melts,and the Si-or B-free-bonding for single crystal superalloys could be realized.Studying the Hf-rich melts also leads to the development of unidirectionally solidified lamellar Ni3Al/Ni7Hf2 eutectic.The suitable compositions for these eutectic in situ composites are Ni-5.8Al-32Hf and Ni-4Al-26Hf-8Cr-4W.The results showed that the lamellar Ni3Al/Ni7Hf2 eutectic aligned parallel to the direction of solidification were prepared with temparature gradient G=250℃·cm-1 and solidification rate R=5μm·s-1 for the ternary alloy,and G=350℃·cm-1 and R=1μm·s1 for multicomponent alloy.

Key words

Superalloys / MC(2) carbides / Ni5Hf phase / mechanical propertie / phase transformation / hafnium / zirconium / solidification / incipient melting

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ZHENG Yun-rong, CAI Yu-lin, RUAN Zhong-ci, MA Shu-wei. Investigation of Effect Mechanism of Hafnium and Zirconium in High Temperature Materials[J]. Journal of Aeronautical Materials, 2006, 26(3): 25-34

References

蔡玉林,郑运荣.铸造镍基高温合金枝晶间强化机理的研究[J].航空学报,1978,(3):97-110.
郑运荣,蔡玉林.含Hf铸造镍基高温合金中Ni5Hf的转变和次生MC(2)的形成[J].金属学报,1980,16(2):151-158.
蔡玉林,郑运荣.K002和K19H合金组织稳定性的研究[J].航空学报,1980,1(2):89-97.
ZHENG Yun-rong,CAI Yu-lin.Phase transformation in hafnium-bearing cast nickel-base superalloys[A].Tien J K,et al.Superalloys 1980[C].Ohio:ASM,1980.465-472.
马淑琴,郑运荣,蔡玉林.铸造镍基高温合金中Ni5Zr的溶解与转变[J].金属学报,1981,17(5):151-158.
蔡玉林,郑运荣.高温合金的金相研究[M].北京:国防工业出版社,1986.119-142.
郑运荣,张德堂.高温合金与钢的彩色金相研究[M].北京:国防工业出版社,1999.141-203.
郑运荣,蔡玉林.影响铸造镍基高温合金中温持久性能的某些因素[D].北京:中国航空科技文献HJB830117,1983.
ZHENG Yun-rong,WANG Yu-ping,XIE Jiz-hou,et al.Effect of chemistry modifications and heat treatments on the mechanical properties of DS Mar-M200 superalloy[A].Reichman S,et al.Superalloys 1988[C].Pennsylvania:TMS,1988.335-344.
郑运荣,蔡玉林,阮中慈.铸造镍基合金中以Zr代Hf的研究[J].金属学报,1987,23(5):A430-433.
郑运荣,蔡玉林,王罗宝.影响含Hf定向凝固合金初熔的某些因素[J].金属学报,1983,19(3):A190-196.
郑运荣.DZ22定向高温合金的初熔及其控制[J].航空学报,1986,7(5):482-489.
ZHENG Yun-rong,WANG Luo-bao,LI Cheng-gong.Influence of carbon content and solidification condition on incipient melting of DS superalloy Mar-M200[J].Chin.J Met Sci Technol,1989 (2):90-95.
郑运荣,蔡玉林,高平.微量合金化对K5合金凝固过程的影响[J].航空材料,1983,3(1):23-29.
郑运荣,陈红.DZ3及其改型定向凝固合金的凝固特性[J].航空材料,1985,(1):10-16.
郑运荣.Hf在铸造高温合金凝固过程中的作用[J].金属学报(A),1986,22(2):119-124.
郑运荣.微量锆对DZ3高温合金凝固行为的影响[J].金属科学与工艺,1988,7(3):40-46.
郑运荣.铪对铸造镍基高温合金焊接裂纹的影响[J].焊接学报,1988,9(3):161-170.
ZHENG Yun-rong,LI Cheng-gong.Skin effect of Hf-rich melts and some aspects in its usage for Hf-containing cast nickel-base superalloys[A].Reichman S,et al.Super-Alloys 1988[C].Pennsylvania:TMS,1988.475-484.
郑运荣,马书伟.富Hf熔体与Al2O3陶瓷的界面反应[J].理学X射线衍射仪用户协会论文选集,1997,(2):65-69.
ZHENG Yun-rong,RUAN Zhong-ci.Microstructure and performance of Ni-Hf brazing filler alloy[J].Acta Metallurgica Sinica (English edition) (B),1990,3 (5):335-340.
ZHENG Y,ZHAO L,TANGRI K.Microstructure of Ni-10Co-8Cr-4W-13Zr alloy and its bonding behavior for single crystal nickel-base superalloy[J].Journal of Materials Science,1993,28:823-829.
ZHENG Yun-rong,RUAN Zhong-ci.Ni-Hf alloys:A new bonding material for single crystal sueralloys[A].Kim S W,Park S J.Fabrication and Characterization of dvanced Materials[C].Seoul:Materials Research Society of Korea,1995.361-366.
RUAN Zhong-ci,WANG Shun-cai,ZHENG Yun-rong.Microstructure and bonding behavior of a new Hf-bearing interlayer alloy for single crystal nickel-base superalloy[J].Scripta Materialia,1996,34 (1):163-168.
MA Shu-wei,ZHENG Yun-rong.Diffusion behavior of hafnium in Ni and Ni3Al[J].Journal of Materials Science Letters,1997,16:1761-1763.
马书伟,郑运荣,于熙泓,等.Ni7Hf2/Ni3Al共晶的微观组织特征[J].中国有色金属学报,1996,6(4):158-162.
马书伟,郑运荣,于熙泓.Al量对Ni-Al-Hf-Cr-W系合金显微组织结构的影响[J].航空学报,1997,18(4):439-443.
MA S W,ZHENG Y R,RUAN Z C.Investigation on Ni3Al-Ni7Hf2 unidirectionally solidified eutectic composites[J].Journal of Materials Science,1999,34:5351-5356.
郑运荣,马书伟,张军,等.Ni3Al+Ni7Hf2定向共晶合金的凝固行为[J].材料工程,2001,(7):3-6.