Among the high-temperature structural materials, the high-temperature titanium alloy has low high-temperature strength, the machinability of C/C composite materials is poor, and the conventional C103, Nb521 and other niobium alloy materials have high density and high price. High strength and low density niobium base alloy avoids the above defects, adding tungsten, molybdenum and other high melting point metal elements to niobium titanium-aluminum alloy to strengthen the alloy. At the same time, a certain low melting point alloying element is added to reduce the density of the alloy. The two measures play a role at the same time, and the alloy can maintain a certain high temperature strength while reducing the density of the alloy, and meet the effect of low specific gravity of the high temperature structural parts.
This niobium alloy material has low density and excellent high temperature strength, which is a potential candidate material for use in high temperature environment. However, this niobium alloy is very sensitive to stress during processing because of many alloying elements and high alloying degree, especially in bar forging, because the surface of the material is affected by tensile stress, it is easy to forge crack, which hinders its popularization and application. At present, when the ingots are prepared by vacuum arc melting, the structure of the ingots cannot be completely balanced due to the fast cooling rate during melting, and the matrix composition will be uneven during solidification, resulting in intragrystalline segregation. In addition, because the raw material inevitably contains a certain amount of gas impurity elements, if the gas is not completely discharged during smelting, pores will be formed inside the ingot. In bar forging, the phenomenon of stress concentration around these microscopic defects is easy to occur, and this niobium alloy has low plasticity, is not easy to deform, and the bar is especially easy to forge crack, so the yield is extremely low and the preparation cost is high, which hinders its popularization and application.
A high-strength and low-density niobium alloy bar is characterized in that it is composed of the following weight percentage components: Ti 29% ~ 31%, Al 4% ~ 6%, W 4% ~ 5%, Cr3% ~ 5%, Zr 0.8% ~ 1.8%, Mo 0.3% ~ 1%, with a margin of Nb and unavoidable impurities; The high strength and low density niobium alloy refers to the room temperature tensile strength of the niobium alloy is 900MPa ~ 1200MPa, and the room temperature elongation is 16% ~ 25%; The tensile strength at 1200℃ is 180MPa ~ 200MPa, and the density is 6.5g/cm3 ~ 7g/cm3.
