【作者】 李建民；

【导师】 魏尊杰；

【作者基本信息】 哈尔滨工业大学 ， 材料加工工程， 2009， 硕士

【摘要】 采用非自耗电极水冷铜坩埚电弧熔炼炉熔炼了不同含Nb量的Ti1100-xNb,并对合金进行了不同工艺的热处理,利用光学显微镜、扫描电子显微镜、能谱、x射线衍射等分析测试手段,研究了不同状态下Ti1100-xNb的微观组织与元素分布情况,并测试了不同状态下Ti1100-xNb的压缩性能。结果表明:Ti1100合金中加入Nb元素后,铸态组织中没有检测出新的相,始终为Ti合金固溶体;晶粒有一定程度的细化,但幅度不大,微观组织为网蓝状组织加部分魏氏组织,片层间富Zr、Mo和Nb;随含Nb量增加,Nb向α片层间富集的趋势越来越大。随着含Nb量增加,铸态Ti1100-xNb合金的延伸率先增加后降低,在0.15%附近有极大值,最大可达18%;抗压强度先降低后增加,在0.2%出现峰值,然后又开始下降;屈服强度总体上呈降低趋势。总体上,Nb含量过高对铸态力学性能不利,在0.15-0.2%之间,对综合性能最有利。热处理后Ti1100-xNb合金的组织均为网蓝组织加魏氏组织,不加Nb时,以网蓝组织为主;加入Nb后,以魏氏组织为主;相同热处理条件下Nb含量增加基本对片层间距没有影响,但会增加魏氏组织的数量。在适合的热处理温度(950℃)下,Nb含量高时,片层间出现富Zr、Si和Mo的析出物。热处理态Ti1100-xNb合金的压缩屈服强度均高于铸态,热处理态压缩屈服强度随含Nb量增加,先降低后增加,在0.1-0.2%之间有一个极值,其中1015℃空冷状态的压缩屈服强度在这一范围内高于不含Nb合金的压缩屈服强度值。含Nb量在0.05-0.1%范围时低温处理(950℃)对延伸率有益。更多还原

【Abstract】 The Ti1100-xNb alloy with different Nb content was produced by non- consumable electrode arc water-cooled copper crucible furnace and treated by different heat treatment process. Mcrostructure and element distribution were studied by optic microscope, scanning electron microscopy, energy spectrum instrument and X-ray diffraction, and the compressive properties of Ti1100-xNb from different process were tested.The results showed that when Nb was added into Ti1100 alloy, there was only titanium solid solution but no new phase detected, and a certain degree of grain refinement could be found a little. The basket weave + widmanstatten structure with the structure characteristics of Ti1100 alloy was obtained. The size between near lamellars was about 1-2μm. The location at these interlamellar interfaces was enriched in zirconium, molybdenum and niobium, and with the increasing of Nb content, the trend of Nb enriched in interlamellar interfaces was growing.The prolongation of Ti1100-xNb alloy presented the trend of first increase then decrease with the increase of the Nb content, which had a max value of 18% at the Nb content of 0.15%. While the compressive stress presented the trend of first decrease then increase with the increase of the Nb content and had a max value at 0.2%, and then presented the trend of decrease with the Nb content continued to grow. The compressive yield stress presented the trend of decrease as a whole. The large Nb content is harmful to the as-cast mechanical performances, and the comprehensive property was best when the Nb content was in 0.15-0.2%.After heat treatment,the basket weave + widmanstatten structure with the structure characteristics of Ti1100 alloy was obtained,and consisted mostly of the basket weave structure. When Nb was added into Ti1100-xNb, the microstructure was still consisted of basket weave and widmanstatten structure, mostly of the widmanstatten structure.There was no effect of the change of Nb content on the lamellar space under the same heat treatment condition; however the number of widmanstatten structure would increase. Under the favorable heat treatment temperature(950℃), when Nb content level was high enough, precipitates rich in Zr,Si and Mo were shown. At the same time the distribution of Nb was not uniform.The compressive yield stress of the Ti1100-xNb alloy after heat treatment was higher than that of as-cast Ti1100-xNb alloy. The compressive yield stress of the Ti1100-xNb alloy after heat treatment presented the trend of first decrease then increase with the increase of the Nb content, and had a max value in 0.1-0.2%. The compressive yield stress of the Ti1100-xNb alloy with the the Nb content in 0.1-0.2% was higher than that of Ti1100 after 1015℃air cooling. When the Nb content was in 0.05-0.1%, low temperature treatment (950℃)was benefit to prolongation.更多还原