Effect of Rare Earth Metals (Y, La) and Refractory Metals (Mo, Ta, Re) to Improve the Mechanical Properties of W-Ni-Fe Alloy-A Review

Abstract

Tungsten heavy alloys are two-phase metal matrix composites that include W-Ni-Fe and W-Ni-Cu. The significant feature of these alloys is their ability to acquire both strength and ductility. In order to improve the mechanical properties of the basic alloy and to limit or avoid the need for post-processing techniques, other elements are doped with the alloy and performance studies are carried out. This work focuses on the developments through the years in improving the performance of the classical tungsten heavy alloy of W-Ni-Fe through doping of other elements. The influence of the percentage addition of rare earth elements of yttrium, lanthanum, and their oxides and refractory metals such as rhenium, tantalum, and molybdenum on the mechanical properties of the heavy alloy is critically analyzed. Based on the microstructural and property evaluation, the effects of adding the elements at various proportions are discussed. The addition of molybdenum and rhenium to the heavy alloy gives good strength and ductility. The oxides of yttrium, when added in a small quantity, help to reduce the tungsten's grain size and obtain good tensile and compressive strengths at high temperatures.

Keywords: mechanical properties; microstructure; rare earth element; refractory metal; tungsten heavy alloy.

Figure 1

Variation in (a) tensile strength and (b) elongation with Re addition [50]. Reproduced with permission from Liu et al, Bulletin of Materials Science; published by Springer, 2008.

Figure 2

(a) SEM micrograph showing the presence of undissolved rhenium particles in the conventionally sintered alloy without milling and (b) Energy-Dispersive Spectroscopy pattern of rhenium (Re) particle [51]. Reproduced with permission from Ravi Kiran et al., Journal of Alloys and Compounds; published by Elsevier, 2017.

Figure 3

Microstructure of (a) 90W–7Ni–3Fe and (b) 85W–7Ni–3Fe with 5 wt% of tantalum, showing grain refinement and the presence of porosity [52]. Reproduced with permission from Bose and German, Metallurgical Transactions A; published by Springer, 1988.

Figure 4

Microstructure of 82W–8Mo–8Ni–2Fe sintered at 1500 °C for 480 min: (a) slowly cooled; (b) water-quenched [57]. Reproduced with permission from Kemp and German, Journal of the Less Common Metals; published by Elsevier, 1991.

Figure 5

Variation in mean grain size with sintering holding time [60]. Reproduced with permission from Hsu et al., Journal of Materials Science; published by Springer, 2003.

Figure 6

Microstructure of the W–Ni–Fe-Mo alloy (a) without La and (b) with 0.4% La [71]. Reproduced with permission from Wu et al., International Journal of Refractory Metals and Hard Materials; published by Elsevier, 1999.

Figure 7

Fracture surfaces of the W–Ni–Fe-Mo alloy (a) without La and (b) with 0.4% La [71]. Reproduced with permission from Wu et al., International Journal of Refractory Metals and Hard Materials; published by Elsevier, 1999.

Figure 8

Effect of P on the impact energy of 93W-4.9Ni-2.1Fe [67]. Reproduced with permission from Hong et al., Metallurgical Transactions A; published by Springer, 1991.

Figure 9

Effect of La on the impact energy of the alloy doped with 150 ppm of P [67]. Reproduced with permission from Hong et al., Metallurgical Transactions A; published by Springer, 1991.

Figure 10

Elemental distribution of SEM micrograph on (a) spark-plasma-sintered W-7Ni-3Fe-0.5La₂O₃; (b) Ni; (c) W; (d) Fe; (e) La; and (f) O [75]. Reproduced with permission from Muthuchamy et al., Rare Metals; published by Springer, 2020

Figure 11

SEM micrograph of a mechanically alloyed oxide dispersion of 1 wt% Y₂O₃ in W-5.6Ni-1.4Fe sintered at 1485 °C for 60 min [80]. Reproduced with permission from Ryu et al., Materials Science and Engineering: A; published by Elsevier, 2003.

Figure 12

Variation in grain size in mechanically alloyed and sintered W-5.6Ni-1.4Fe with increasing Y₂O₃ content [80]. Reproduced with permission from Ryu et al., Materials Science and Engineering: A; published by Elsevier, 2003.

Figure 13

The adiabatic shear band is visible in the specimen dynamically tested at a strain rate of 1.9 × 10³ s⁻¹ [87]. Reproduced with permission from Gong et al., Materials Science and Engineering: A; published by Elsevier, 2010.

Figure 14

The SEM and optical micrographs of SPS-sintered alloy with 0.25 wt% yttria-stabilized zirconia (YSZ) [89]. “Reproduced with permission from Muthuchamy et al., Arabian Journal for Science and Engineering; published by Springer”.