热处理对定向凝固Nb-Ti-Si基合金组织及力学性能的影响（英文）

发布时间：2018-03-10 15:18

本文选题：Nb-Ti-Si基超高温合金　切入点：整体定向凝固　出处：《稀有金属材料与工程》2017年01期 　论文类型：期刊论文

【摘要】：在熔体温度为2323 K,抽拉速率为100μm/s的条件下对Nb-Ti-Si基超高温合金进行了有坩埚整体定向凝固(DS),然后对定向凝固试样进行了2种不同工艺的热处理:即1723 K/50 h高温均匀化处理(HT1)和1623 K/50 h+1723 K/50 h+1373 K/50 h复合热处理(HT2)。采用XRD,SEM和EDS等分析手段研究热处理对定向凝固合金微观组织及其力学性能的影响。结果表明,热处理后合金中大尺寸初生硅化物的体积分数下降,2种方式的热处理均能有效减轻甚至消除合金中的成分偏析。热处理后原DS试样中Nbss+(Nb,X)_5Si_3共晶胞的边界完全消失。相比HT1处理,HT2处理后试样中硅化物的分布更加均匀。与DS试样相比,经HT2处理后试样的室温断裂韧性值增加了12.3%(约19.2 MPa·m~(1/2)),且其抗拉伸强度增加了26.6%(最大值达到933.2 MPa)。力学性能的改善主要归因于热处理后组织中(Nb,X)_5Si_3颗粒弥散分布以及韧性Nbss相的形状、尺寸及含量均发生变化。
[Abstract]:Under the condition of melt temperature 2323K and pulling rate 100 渭 m / s, directional solidification of Nb-Ti-Si based ultra high temperature alloy with crucible was carried out. Then two different heat treatment processes were carried out on the directional solidified sample: 1723 K / 50 h high temperature homogenization. The effect of heat treatment on the microstructure and mechanical properties of directionally solidified alloy was studied by XRDX SEM and EDS, respectively, and 1623K / 50 h 1723K / 50h 133K / 50h composite heat treatment was used to study the effect of heat treatment on the microstructure and mechanical properties of directionally solidified alloy. After heat treatment, the decrease of volume fraction of large size primary silicide in the alloy can effectively reduce or even eliminate the segregation of the composition of the alloy. After heat treatment, the boundary of the Nbss NbCX / Si5Si3 eutectic cell completely disappears in the original DS sample. The distribution of silicides in the samples treated with HT1 was more uniform than that of the samples treated with HT1, and the distribution of silicides was more uniform than that of the samples treated with DS. After HT2 treatment, the fracture toughness at room temperature increased by 12.3and the tensile strength increased by 26.6 (the maximum value was 933.2 MPA). The improvement of mechanical properties was mainly attributed to the dispersion distribution of NbBX _ X _ 5Si _ 5Si _ 3 particles and the shape of ductile Nbss phase in the microstructure after heat treatment. The size and content are changed.
【作者单位】：西北工业大学凝固技术国家重点实验室;
【基金】：National Natural Science Foundation of China(51371145,51071124) “111”Project(B080401)
【分类号】：TG132.3;TG166.7

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