共查询到18条相似文献,搜索用时 62 毫秒
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本文对一种新型镍基抗热腐蚀长寿命定向凝固合金的显微组织进行了研究,对铸态及热处理态各组成相的分布和形态作了分析说明. 相似文献
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采用透射电子显微镜研究GH159合金固溶处理后的显微组织,观察到晶内和晶界有M23C6相,有序弥散的球形γ‘相,密排六方交叉网状组织ε相。而洛氏硬度和ε相的间距随着固溶温度和蔼同而增大变工,随着固溶时间的延长而增大。 相似文献
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通过测定一种单晶镍基高温合金的高温拉伸蠕变曲线和位错运动的内摩擦应力σ0,建立了综合蠕变方程,计算出不同蠕变阶段的激活能和相关参数.结果表明在蠕变期间,内摩擦应力σ0随外加应力σ的增加而略有提高,但随温度升高而明显下降.在实验温度和应力范围内,在不同蠕变阶段,具有不同的激活能Q,时间指数m和结构常数Bi.因此,合金在不同蠕变阶段具有不同的蠕变机制.蠕变初期,形变机制是位错在基体通道中运动;而大量位错切入筏状γ'相中是蠕变第3阶段的主要特征,在γ'/γ两相界面产生空洞及空洞的聚集和微裂纹扩展是蠕变断裂的直接原因. 相似文献
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郭宁 《有色金属材料与工程》1998,19(2):64-69
本文设计了新型铸造合金的化学成分,采用金相显微镜、X射线衍射、电于探什(EMPA)、透射电镜(TEM)、扫描电镜(SEM)及扫描隧道显微镜(STM)研究了新型铸造合金的组织及其腐蚀行为。试验结果表明,该合金经1200t固溶处理后,可得到单一的奥氏体组织,具有良好的耐蚀性能。通过STM的观测,得到了新型合全的超高分辨三维腐蚀形貌图象。 相似文献
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高温长期时效对钴高温合金GH605组织与性能的影响 总被引:1,自引:1,他引:0
研究了长期时效处理对钴基高温合金GH605组织与性能的影响。结果表明,815℃长期时效过程中,随时效时间的延长,析出碳化物(主要是M6C)逐渐增多,而且时效500h后发现有少量针状或棒状Laves相析出。高温塑性,尤其是室温塑性的下降与碳化物过分粗化以及脆性Laves相的析出并增多有关,但这两个因素对于室温拉伸强度及高温持久寿命的影响较小。为了使合金塑性得到恢复,可以采用重新固溶处理的措施。 相似文献
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S. P. Coryell K. O. Findley M. C. Mataya E. Brown 《Metallurgical and Materials Transactions A》2012,43(2):633-649
Superalloys are being employed in more extreme conditions requiring higher strength, which requires producers to forge products
to finer grain sizes with less grain size variability. To assess grain size, crystallographic texture, and substructure as
a function of forging conditions, frictionless uniaxial compression testing characteristic of hot working was performed on
INCOLOY 945 (Special Metals Corporation, Huntington, WV), which is a newly developed hybrid of alloys 718 and 925, over a
range of temperatures and strain rates. The microstructure and texture were investigated comprehensively using light optical
microscopy, electron backscatter diffraction (EBSD), electron channeling contrast imaging (ECCI), and transmission electron
microscopy (TEM) to provide detailed insight into microstructure evolution mechanisms. Dynamic recrystallization, nucleated
by grain/twin boundary bulging with occasional subgrain rotation, was found to be a dominant mechanism for grain refinement
in INCOLOY 945. At higher strain rates, static recrystallization occurred by grain boundary migration. During deformation,
duplex slip along {111} planes occurred until a stable 〈110〉 fiber compression texture was established. Recrystallization
textures were mostly random but shifted toward the compression texture with subsequent deformation. An exception occurred
at 1423 K (1150 °C) and 0.001 seconds−1, the condition with the largest fraction of recrystallized grains, where a 〈100〉 fiber texture developed, which may be indicative
of preferential growth of specific grain orientations. 相似文献
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利用卧式挤压机对GH625合金进行了管材热挤压试验,研究了挤压温度和挤压比对GH625合金管材挤压过程中的力能参数及挤压后管材不同部位的显微组织的影响.结果表明,随着挤压温度的降低和挤压比的升高,最大挤压力逐渐升高.管坯在固定挤压速度40 mm·s-1,预热温度为1150~1200℃和挤压比为3.46~4.10的条件下,可成功挤压出3种规格的GH625合金管材;挤压后的管材由于在挤压过程中发生了动态再结晶组织明显细化,管坯横向组织为等轴的动态再结晶晶粒和原始晶粒组成,纵向组织则由等轴的动态再结晶晶粒及被拉长的原始晶粒组成,呈条带状组织;挤压后管材的外壁、中心、内壁与管材的头部、中部与尾部在热挤压变形过程中,由于变形不均匀发生了不同程度的再结晶,因而存在不同程度的混晶组织.为消除混晶组织,结合设备能力与GH625合金的变形特征,可通过提高坯料挤压的变形温度和挤压比来控制变形的均匀性,并通过切头,去尾和对管材内壁进行少量机加工的方法,可获得具有完全动态再结晶组织的挤压管材. 相似文献
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采用SEM、极化曲线和XRD研究了在锌浴中添加Sn、Ni元素后含0.36% Si钢热浸镀锌合金镀层的组织及耐蚀性能的变化.结果表明:Zn-Sn-Ni合金浴法能够有效抑制含硅活性钢镀层的快速生长,获得厚度适宜、组织致密的镀层.Zn-Ni-Sn合金镀层在5%NaC1溶液中发生自发腐蚀的倾向小于Zn镀层,其极化电阻增大,腐蚀... 相似文献
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The hot strength and short‐time creep resistance of austenitic steel CN0.85 with about (mass%) 18Cr, 18Mn, 0.6N, and 0.25C was investigated up to 700°C together with the corresponding structural changes of the solution annealed or cold worked initial states. In the primary creep range, the creep rate was rapidly reduced to the minimum creep rate and the more so after initial cold working. This also lowered the minimum creep rate but hardly the time to fracture. Precipitation of carbides and nitrides occurred in or near grain boundaries which gave rise to creep cracks. Precipitates within the grains, visible only in the overaged state, are assumed to have raised the resistance to creep. Comparing the creep strength of CN0.85 with standard hot work tool steel H11 points to an advantage of the former at service temperatures of >550°C. However, tests in practice are required to back up the favorable results of this tentative study. 相似文献
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高铌TiAl基合金板材制备包套热轧工艺及组织控制 总被引:1,自引:1,他引:0
采用新的包套热轧工艺方法,在普通轧机上成功制备出厚度为1.9 mm的高铌钛铝合金薄板,总变形量达到80%以上。整个轧制过程保持在近等温的状态下,平均轧制速率小于80 mm.s-1。显微组织观察表明,薄板组织均匀,轧制变形后的晶粒度略大于合金变形前的晶粒度。在动态再结晶与道次间回炉处理时发生的静态再结晶两种机制的作用下,发生了完全再结晶,因而不再具备变形组织的带状特征。板材的取向图显示存在100晶向平行于轧制方向的晶粒,其余晶粒的取向则呈现随机分布。锻态高铌钛铝合金包套热轧后织构组分存在{100}010的立方织构,这种织构是由再结晶引起的。 相似文献