Effect of W addition on compressive strength of Nb-10Mo-10Ti-18Si-base in-situ composites
Effect of W addition on compressive strength of Nb-10Mo-10Ti-18Si-base in-situ composites
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DOI：
10.2320/matertrans1989.41.1125
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发表时间：
2000-09
期刊：
影响因子：
--
通讯作者：
J. Sha;H. Hirai;T. Tabaru;A. Kitahara;Hidetoshi Ueno;S. Hanada
中科院分区：
文献类型：
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作者：
J. Sha;H. Hirai;T. Tabaru;A. Kitahara;Hidetoshi Ueno;S. Hanada
铌固溶体/铌硅化物原位复合材料作为高温结构材料具有广阔的应用前景。为了进一步提高Nb-10 Mo-10 Ti-18 Si共晶合金的高温强度，我们尝试在共晶合金中添加W，分别以0、5、10和15mol%W替代Nb。采用电弧铸造法制备了Nb-10 Mo-10 Ti-18 Si共晶合金，并对部分样品进行了浮区熔炼定向凝固，生长速率为15 mm/h。测试了材料的维氏硬度和高温抗压强度。不加W的试样由Nb的共晶固溶体和（Nb，Mo，Ti）5Si 3硅化物组成，而Nb的初晶固溶体是W取代Nb的结果。定向凝固样品的显微组织是粗的，并且在生长方向上取向，但它们没有显示出在定向凝固材料的情况下经常观察到的典型显微组织。随着W含量的增加，合金的硬度增加。随着W含量的增加，1670 K时的0.2%屈服强度（σ 0.2）和比0.2%屈服强度（σ 0.25）（σ 0.2除以密度）显著增加。定向凝固试样的σ 0.2和σ 0.2S均高于电弧铸造试样。即使在1770 K下，具有15 mol% W的定向凝固样品也显示出约650 MPa的σ 0.2。
Niobium solid solution/niobium silicides in-situ composites are expected to have applications in the future as high-temperature structural materials. To improve the high temperature strength further, we tried to add tungsten to Nb-10Mo-10Ti-18Si eutectic alloy by replacing Nb with 0, 5, 10 and 15 mol%W, The samples were prepared by arc casting and some of them were directionally solidified by the floating zone melting technique at a growth rate of 15 mm/h, After annealing at 1870 K for 100h, the microstructure, Vickers hardness and high-temperature compressive strength were examined. The samples without W consisted of eutectic Nb solid solution and (Nb, Mo, Ti) 5 Si 3 silicide, while primary Nb solid solution appeared as a result of substituting W for Nb. The microstructure of directionally solidified samples was coarse and oriented in the direction of growth, but they did not show the typical microstructure often observed in the case of directionally solidified materials. The Vickers hardness increased with increasing W content. The 0.2% yield strength (σ 0.2 ) and the specific 0.2% yield strength (σ 0.25 ) (σ 0.2 divided by the density) at 1670 K increased markedly with increasing W content. The directionally solidified samples showed higher σ 0.2 and σ 0.2S than the arc-cast samples. Even at 1770 K, the directionally solidified sample with 15 mol% W showed σ 0.2 of about 650 MPa.