【作者】 韩昶；

【导师】 范志康；

【作者基本信息】 西安理工大学 ， 材料科学与工程， 2008， 硕士

【摘要】 蒙乃尔（Monel）合金是以金属镍为主,金属铜为辅的镍基合金,该合金具有很好的抗腐蚀及良好的力学等性能。本文在真空熔炼条件下,通过添加硼和稀土铈元素,研究了B、Ce对含Si蒙乃尔合金组织及性能的影响。研究得出以下结论:1.未添加微量元素制备的含Si蒙乃尔铸态合金的主要组织为:树枝状α基体、弥散分布于基体的β-Ni₃Si相以及分布于晶界和枝晶间的蜂窝状（α+β-Ni₃Si）共晶。2.分别添加微量元素B、Ce后,在0.00～0010wt%范围内,随着B、Ce含量的增加,合金枝晶组织开始细化,（α+β-Ni₃Si）共晶组织形貌由网状向断网状演变;当B、Ce含量分别达到0.03wt%时,枝晶组织明显细化,共晶组织形貌呈断网状。3.在0.00～0.10wt%B范围内,随着B含量的增加,合金的腐蚀电位逐渐正移,腐蚀电流亦逐渐减小;B含量达到0.03wt%时,合金的腐蚀电位最高,腐蚀电流最小,合金表面钝化膜致密;在0.00～0.10wt%Ce范围内,随着Ce含量的增加,合金的腐蚀电位逐渐正移,腐蚀电流逐渐减小;Ce含量达到0.03wt%时,合金的腐蚀电位较高,腐蚀电流较小,由于稀土铈参与成膜,合金表面钝化膜较致密;进一步增加Ce含量,合金的腐蚀电位正移趋势逐渐平缓,腐蚀电流下降趋势亦逐渐平缓。4.在0.00～0.10wt%范围内,随着B、Ce含量的增加,合金的平均硬度先增大后降低;当B、Ce含量分别达到0.03wt%时,合金的平均硬度达到最高值分别为344HB和335HB。5.B在含Si蒙乃尔合金中主要起到变质剂的作用,且最佳添加量0.03wt%;Ce在含Si蒙乃尔合金中主要起到净化剂的作用,且最佳添加量0.03wt%。6.固溶温度在820℃～1120℃之间,含硼0.03wt%合金及含铈0.03wt%合金随着固溶温度的升高,其合金元素开始均匀化扩散,晶界处的β-Ni₃Si相的数量明显减少;当固溶温度达到1020℃时,枝晶偏析得到完全消除,晶界处的β-Ni₃Si相完全溶解;随着固溶温度的进一步升高,当温度达到1120℃时,晶界因熔化而出现了鱼骨状过烧组织。7.固溶温度在820℃-1120℃之间,含硼0.03wt%合金及含铈0.03wt%合金随着固溶温度的升高,合金腐蚀电位逐渐增大,腐蚀电流急剧变小;当固溶温度为1020℃时,合金腐蚀电位最高,腐蚀电流最小。8.时效温度在500℃-700℃之间,含硼0.03wt%合金及含铈0.03wt%合金随着时效温度的升高,合金中的β-Ni₃Si强化相的数量逐渐增加,硬度也随之增大;在时效温度为600℃时,β-Ni₃Si强化相析出的数量最多,合金硬度最高,其中含硼0.03wt%合金硬度最高值为361HB,含铈0.03wt%合金硬度最高值为357HB;时效温度为700℃时,合金中的部分β-Ni₃Si相聚集长大,合金硬度降低。9.初步认为含硼0.03wt%合金及含铈0.03wt%合金最佳热处理工艺是:1020℃固溶4h,油冷;然后600℃时效处理4h,空冷。更多还原

【Abstract】 Monel alloys are the nickel alloys within main element of nickel and secondary element of copper.The alloys have better corrosion resistance,better mechanical property,etc.By means of vacuum melting,Monel alloys with addition Boron and Cerium is investigated into the microstructure and properties of the alloy in present paper.The following conclusions can be drawn from those investigations:1.The as-cast microstmcture of the Monel alloy with silicon consists of dendritic a matrix, dispersedβ-Ni₃Si phase and honeycomb-like eutectic（α+β-Ni₃Si）on grain boundary and in interdendritic regions.2.After individually adding B and Ce trace element in the alloy,the dendrites gradually refine with increasing B,Ce in the range of 0～0.10wt%,while the eutectic structure evolves from netlike shape to disconnected netlike shape slightly.When the B,Ce additive individually reaches 0.03wt%,the dendrites refine significantly and the eutectic structure has disconnected netlike shape.3.The corrosion potential of the alloy gradually shifts to positive value,while the corrosion current gradually decreases in the range of 0～0.10wt%B.When B additive is 0.03wt%,the corrosion potential of alloy is the highest and the corrosion current is the lowest and the passivating is the best compaction film.The corrosion potential of the alloy gradually shifts to positive value,while the corrosion current gradually decreases in the range of 0～0.10wt%Ce.When Ce additive is 0.03wt%,the corrosion potential of alloy is the higher and the corrosion current is the lower and the passivating is the better compaction film because of the film involving in Ce.With further increasing the content of Ce,the corrosion potential of alloy begins to gently shift positive value and the corrosion current gently decreases.4.With the increase of B and Ce,the hardness of the alloy firstly increases then decreases in the range of 0～0.10wt%.When the B additive reaches 0.03wt%,the alloys get the highest hardness 344HB.While the Ce additive reaches 0.03wt%,the alloys get the highest hardness 335HB.5.Trace B element plays a Strong inoculating role in the Monel alloy with silicon and the best addition is 0.03wt%.Trace Ce element plays a strong purifying role in the Monel alloy with silicon and the best addition is 0.03wt%.6.The alloy elements of 0.03wt%B and 0.03wt%Ce begin to diffuse uniformly and theβ-Ni₃Si phase decrease obviously on grain boundary with the increase of the solution temperature in the range of 820℃～1120℃.When the solution temperature is 1020℃,the dendritic segregation has been slaked wholly andβ-Ni₃Si phase are fully dissolved on grain boundary.With further increasing the solution temperature,the alloy appears burnt structure because of grain boundary melting.7.The alloy corrosion potential of 0.03wt%B and 0.03wt%Ce gradually shifts to positive value,while the corrosion current sharply decreases with the increase of the solution temperature in the range of 820℃～1120℃.When the solution temperature is 1020℃,the corrosion potential of alloy is the highest and the corrosion current is the lowest.8.The amount ofβ-Ni₃Si is strengthening phases of 0.03wt%B alloy and 0.03wt%Ce alloy with increasing of the aging temperature in the range of 500℃～700℃aging temperature. The largest quantity and the highest hardness can be got at 600℃,which is 361HB of the alloys with 0.03wt%B and is 357HB of the alloys with 0.03wt%Ce.Theβ-Ni₃Si phases begin to aggregate while aging at 700℃which result in decrease of hardness.9.From the experiments,it can be considered that the optimizational heat treatment technology is:solid solution treatment at 1020℃for 4h by oil cooling and then aging treatment at 600℃for 4h by air cooling.更多还原