5-24. The investigation of preparation and performance of FeCrAl alloy: application of materials genome initiative

Yingjie Qiao

Harbin Engineering University

Abstract: Since China has promoted the special project of Materials Genome Initiative (MGI), it made good progress in many research fields. This project relies on the national key R&D plan "Advanced nuclear fuel cladding material genome multi-scale software design development and application demonstration", the main work includes the preparation and performance of FeCrAl cladding materials and optimization of material composition and preparation process. Through microstructure characterization and property measurement, our group analyzed the influence of alloy composition on the thermo-mechanical properties, and established the corresponding relationship of the composition-structure-performance of the FeCrAl alloy. Specific research contents are as follows:

(1) Optimization of the FeCrAl alloy components with MGI method. With the help of artificial neural network algorithm, which has high fault tolerance and robustness, the MGI based simulation software was developed to realize the intelligent material design. The physical properties of FeCrAl alloys are often determined by factors such as structural and process conditions at different scales. Therefore, the multi-scale calculation method was used as the main method to theoretically study the structure and properties of FeCrAl superalloy from different time and space scales, then establish theoretical models and explore the relationship between material damping performance and its composition and process conditions. The high-throughput theoretical calculations were applied and continuously fed back and optimized through the genetic algorithm. Finally, the components intervals and process conditions of the alloy design are screened out.

(2) FeCrAl alloy ingot with target composition is prepared by vacuum induction melting method, and then the hot rolling and recrystallization annealing are applied for grain size controlling. The preparation processes include industrial raw material treatment, smelting, refining, pouring, vacuum induction furnace treatment, demolding. The main metal components of the alloy were detected by inductively coupled plasma optical emission spectrometer (ICP-AES). The contents of carbon, sulfur, oxygen and nitrogen were determined. The FeCrAl alloy was homogenized and annealed at 1150℃ using a trolley furnace. Then it was rolled at 800°C on a two-roll reversible hot rolling test with 55% deformation. Thereafter, a recrystallization annealing at 1000℃ for 1 h was carried out with trolley furnace.

(3) The mechanical properties of FeCrAl alloys refer to GBT 228.1-2010 and GBT 228.2-2015. The tensile strength of different compositions samples at normal temperature is 340MPa~520MPa, the elongation at break is 10%~35%, the tensile strength at 350°C is 350MPa~450MPa, and the elongation at break is 23%~30%. FeCrAl alloy thermal performance standards reference ASTM-E-1461-01. At room temperature, the thermal conductivity of FeCrAl alloys is 12~21 W/(m∙K), and the thermal diffusivity is 3.5~5.9 m²/s. At 350°C, its thermal conductivity is 17~25 W/(m∙K), and the thermal diffusivity is 3.7~5.3 m² / s.

Above is the preparation and testing of the FeCrAl alloy suitable for the MGI method. It is hoped that it will be helpful for the research and development of new products from MGI projects.

Keywords：Materials genome initiative；FeCrAl；Vacuum melting；Thermo-mechanical performance

材料基因工程FeCrAl合金块体制备及测试

乔英杰*

哈尔滨工程大学

摘要：自从我国推进材料基因工程专项以来，多个研究方向均取得了良好的进展。本课题依托国家重点研发计划“先进核燃料包壳的材料基因组多尺度软件设计开发和应用示范”，开展Fe-Cr-Al包壳材料的制备及性能研究，优化材料的组成和制备工艺。通过对材料微观结构的表征和材料的性能的测试，分析合金成分对材料热-力学性能的影响规律，建立材料的成分-结构-性能的对应关系，具体内容如下：

（1）首先使用材料基因的方法设计优化出Fe-Cr-Al合金的主要成分。基于材料基因设计思想，以人工神经网络算法为基础，利用其高容错性和健壮性，编制出材料基因计算软件，从而实现智能化的材料设计。而Fe-Cr-Al 阻尼合金的物理性质往往由不同尺度的结构和工艺条件等因素共同决定。因此，我们以多尺度计算方法为主要手段，从不同时空尺度上对Fe-Cr-Al高温合金的结构和性能进行理论研究，建立理论模型，探求材料阻尼性能与其成分、组成、工艺条件之间的关联。通过高通量制备建立理论模型基础并通过遗传算法不断反馈优化理论模型。通过理论计算筛选出设计需要的成分区间和工艺条件。

（2）然后采用真空感应熔炼方法制备目标成分的Fe-Cr-Al合金铸锭，然后通过热轧、再结晶退火得到晶粒大小可控的Fe-Cr-Al合金。具体的工艺流程包括原料处理、熔炼、精炼、浇注、破真空、脱模等。采用电感耦合等离子体发射光谱仪 ( ICP-AES ) 检测合金主要金属成分，采用红外碳硫分析仪测定了碳、硫含量，采用氧氮分析仪测定了氧、氮含量，将成分合格的产品进行下一步加工。使用台车炉对Fe-Cr-Al合金进行1150℃均匀化退火。铸锭开坯后在二辊可逆热轧实验机组上在800℃下形变量55%进行轧制。之后使用台车炉进行1000℃下1h再结晶退火，最终得到目标样品。

（3）Fe-Cr-Al合金力学性能标准参考GBT 228.1-2010和GBT 228.2-2015。不同组分配比样品的常温抗拉强度在340~520MPa，断裂伸长率在10~35%，350℃抗拉强度在350~450MPa，断裂伸长率在23~30%。在Fe-Cr-Al合金热学性能标准参考ASTM-E-1461-01，其室温热导率在12~21W/(m∙K)，热扩散系数在3.5~5.9m²/s。其350℃热导率在17~25W/(m∙K)，热扩散系数在3.7~5.3 m²/s。

以上是我们提出的适用于材料基因专项Fe-Cr-Al合金的制备及测试，希望对形成带有材料基因工程项目特色的新型产品的研发有所借鉴与帮助。

关键词：材料基因工程；FeCrAl；真空熔炼；热-力学性能测试