Effect of W Addition on Compressive Strength of Nb&amp;ndash;10Mo&amp;ndash;10Ti&amp;ndash;18Si-Base &lt;I&gt;In-Situ&lt;/I&gt; Composites

Sha, Jiangbo; Hirai, Hisatoshi; Tabaru, Tatsuo; Kitahara, Akira; Ueno, Hidetoshi; Hanada, Shuji

doi:10.2320/matertrans1989.41.1125

Cited by 16 publications

(15 citation statements)

References 7 publications

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“…In this decade, significant progress has been achieved in understanding the mechanical behavior of Nb-base in-situ composites, such as their high temperature compression properties, 6,7) high temperature tensile properties 8,9) and room temperature fracture toughness. 10) However, there are only a few reports available on the hardness, H, and elastic modulus, E, of the constituent phases of Nb SS /Nb 5 Si 3 in-situ composites, despite of the importance of the property for material design, especially for fracture toughness improvement.…”

Section: Introductionmentioning

confidence: 99%

Evaluation Technique of the Hardness and Elastic Modulus of Materials with Fine Microstructures

2003

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Quantitative data of mechanical properties such as hardness, H, and elastic modulus, E, are required for the constituent phases of an alloy in the process of alloy design. To meet the needs, the evaluation technique of H and E of phases in composites through nanoindentation tests is proposed. Moreover, H and E of Nb solid solution (Nb SS ) and niobium silicide (Nb 5 Si 3 ) phases in Nb-base in-situ composites were characterized by the proposed method. To clarify the quantitative relationship between the nanohardness, Hn, and the micro-Vickers hardness, Hv, nanoindentation tests were carried out on the Hv Standard blocks with Hv100, 500, 700, 900 and 1600, under a wide range of applied loads from 0.1 to 40 mN. As a result, it was clarified that Hv and Hn are linearly related under each applied load. Therefore, Hv could be estimated from Hn by applying the linear relation. It was also confirmed that the elastic modulus is almost independent of the applied loads. Therefore, the elastic modulus, E, could also be directly estimated by nanoindentation tests with Poisson's ratios of tested materials. Hv and E of Nb SS and Nb 5 Si 3 in the Nb-base composites determined by the method show good agreement with the reported values for both phases. Accordingly, it is possible to conclude that the proposed method is useful to quantitatively evaluate the hardness and elastic modulus of constituent phases in a composite.

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Section: Introductionmentioning

confidence: 99%

Evaluation Technique of the Hardness and Elastic Modulus of Materials with Fine Microstructures

2003

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“…However, the tensile strength of W15 dropped remarkably to 177 MPa, nearly the same as that of W-free, showing a slight increment. It is worth noting that the increments of tensile strength of these composites are insignificant compared with those of the compression strength of this alloy system [8]. This result implies that the W additions give a marked positive effect on the improvement of compression strength.…”

Section: Estimation Of Hardness and Elas-tic Modulusmentioning

confidence: 75%

“…Based on its relatively low density of 8.57 Mg/m 3 compared to that of Ni and good ambient temperature ductility, many researchers have made special efforts to develop various Nb base refractory superalloys since the 1960s [2]. In Nb base alloys, the potential possibility of improving their elevated temperature strength further by means of combining them with intermetallics such as silicide [3][4][5][6][7][8] and alumide [9][10][11] still exists.…”

Section: Introductionmentioning

confidence: 99%

“…The reports with respect to an evaluation of the properties of refratory Nb base in-situ composites are mainly concerned with the compression test at elevated temperatures [8,[12][13][14]. To broaden the practical application of refractory Nb base in-situ composites to high temperature components, it inevitably requires a sufficient understanding of their tensile properties at elevated temperatures.…”

Section: Introductionmentioning

confidence: 99%

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Effects of tungsten addition on tensile properties of a refractory Nb−18Si−10Ti−10Mo−xW (x=0,5, 10 and 15 mol.%)in-situ Composites at 1670 K

2002

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To investigate the effect of tungsten addition on mechanical properties, we prepared refractory (62-x)Nb18Si-10Mo-10Ti-xW (x=0, 5, 10 and 15 mol.%) in-situ composites by the conventional arc-casting technique, and then explored the microstructure, hardness and elastic modulus at ambient temperature and tensile properties at 1670 K. The microstructure consists of relatively fine (Nb, Mo, W, Ti) 5 Si 3 silicide and a Nb solid solution matrix, and the fine eutectic microstructure becomes predominant at a Si content of around 18 mol.%. The hardness of (Nb, Mo, W, Ti) 5 Si 3 silicide in a W-free sample is 1680 GPa, and goes up to 1980 GPa in a W 15 mol.% sample. The hardness, however, of Nb solid solution does not exhibit a remarkable difference when the nominal W content is increased. The elastic modulus shows a similar tendency to the hardness. The optimum tensile properties of the composites investigated are achieved at W 5 mol.% sample, which exhibits a relatively good ultimate strength of 230 MPa and an excellent balance of yield strength of 215 MPa, and an elongation of 3.7%. The SEM fractography generally indicates a ductile fracture in the Wfree sample, and a cleavage rupture in W-impregnated ones.

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“…In this decade, a significant progress has been achieved in understanding the mechanical behavior of Nb-base in-situ composites; the compression strength of Nb-Si-Mo-Ti-W alloys reaches up to 930 MPa at 1670 K, 1) that of Nb-Si-TiMo alloys to 1000-1500 MPa at 1470 K 2) and the nominal fracture toughness (K Q ) of Nb-Si-Mo alloys indicates 5.5-11.5 MPa·m 1/2 .…”

Section: Introductionmentioning

confidence: 99%

Mechanical Properties of Nb-18Si-5Mo-5Hf-2C <I>In-Situ</I> Composite Prepared by Arc-Casting Method

et al. 2002

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Niobium-base in-situ composite, Nb-18Si-5Mo-5Hf-2C (in mol%), was fabricated by arc-casting method and heat-treated at 2070 K for 20 h in vacuum. The microstructure is composed of Nb solid solution (Nb SS ) matrix phase and secondary phase of Nb 5 Si 3 . The Nb 5 Si 3 was found to have two kinds of structure: one is the α phase reported in the Nb-Si binary phase diagram and the other is a hexagonal phase with Mn 5 Si 3 -type structure. To evaluate the mechanical properties of the composite, nano-indentation hardness tests and tensile tests were conducted. The hardness and elastic modulus at ambient temperature were evaluated using nano-indentation hardness tester and the tensile properties were examined by an Instron-type materials testing machine at temperatures of 300, 1470, 1570, 1670 and 1770 K, and at an initial strain rate of 1 × 10 −4 s −1 . The hardness and elastic modulus of the Nb SS phase are 480 GPa and 170 GPa and those of the silicide are 1480 GPa and 380 GPa. The composite exhibited the excellent ultimate tensile strength of 450 MPa at 1470 K, and the brittle to ductile transition temperature is between 1470 and 1570 K. The fracture behavior of the in-situ composite is complex, however, involving cleavage of the Nb 5 Si 3 , Nb SS /Nb 5 Si 3 interface separation, ductile rupture of the Nb SS and correlations of these.

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Effect of W Addition on Compressive Strength of Nb–10Mo–10Ti–18Si-Base <I>In-Situ</I> Composites

Cited by 16 publications

References 7 publications

Evaluation Technique of the Hardness and Elastic Modulus of Materials with Fine Microstructures

Evaluation Technique of the Hardness and Elastic Modulus of Materials with Fine Microstructures

Effects of tungsten addition on tensile properties of a refractory Nb−18Si−10Ti−10Mo−xW (x=0,5, 10 and 15 mol.%)in-situ Composites at 1670 K

Mechanical Properties of Nb-18Si-5Mo-5Hf-2C <I>In-Situ</I> Composite Prepared by Arc-Casting Method

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