Strong-yet-ductile chemically complex alloy over a wide temperature range and its preparation method

Abstract

The present invention relates to a strong-yet-ductile chemically complex alloy over a wide temperature range, including nickel, cobalt, iron, chromium, aluminum, titanium, tantalum, niobium, tungsten, molybdenum, and one or more infinitesimal elements. The strong-yet-ductile chemically complex alloy forms one or more multi-scale L1 2 particles within a grain interior and exhibits serrated grain boundaries via controlling a heat treatment process. The aluminum, titanium, tantalum and niobium facilitate the formation of the one or more multi-scale L1 2 particles, the tungsten and molybdenum enhances a strength of a FCC matrix of the chemically complex alloy, and the one or more infinitesimal elements improve a cohesive strength of the serrated grain boundaries. The present invention has the potential to pave the way for the creation of a range of CCAs exhibiting enhanced strength and ductility across a broad temperature spectrum, achieved by integrating high-density multiscale L1 2 particles and serrated grain boundaries.

What is claimed is: 
     
         1 . A strong-yet-ductile chemically complex alloy over a wide temperature range, comprising:
 35-45 at. % of nickel;   15-25 at. % of cobalt;   5-10 at. % of iron;   5-15 at. % of chromium;   5-10 at. % of aluminum;   3-8 at. % of titanium;   0.5-3 at. % of tantalum;   0.3-2 at. % of niobium;   0.3-2 at. % of tungsten;   0.3-2 at. % of molybdenum; and   one or more infinitesimal elements,   wherein the strong-yet-ductile chemically complex alloy forms one or more multi-scale L1 2  particles within a grain interior and exhibits serrated grain boundaries via controlling a heat treatment process,   wherein the aluminum, titanium, tantalum and niobium facilitate the formation of the one or more multi-scale L1 2  particles, the tungsten and molybdenum enhances a strength of a FCC matrix of the chemically complex alloy, and the one or more infinitesimal elements improve a cohesive strength of the serrated grain boundaries.   
     
     
         2 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 1 , wherein the one or more infinitesimal elements comprise boron, zirconium, or hafnium. 
     
     
         3 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 2 , wherein the one or more infinitesimal elements has an atomic percentage ranging from 0.01% to 0.15%. 
     
     
         4 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 1 , wherein the wide temperature range is between −196° C. to 1,000° C. 
     
     
         5 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 4 , when tested at −196° C., the strong-yet-ductile chemically complex alloy achieves an ultimate tensile strength of at least 1500 MPa and along with a ductility of at least 35%. 
     
     
         6 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 4 , when tested at room temperature, the strong-yet-ductile chemically complex alloy achieves a yield strength of at least 700 MPa, an ultimate tensile strength of at least 1,300 MPa, and a ductility of at least 30%. 
     
     
         7 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 4 , when tested at a temperature between 600° C. to 900° C., a phenomenon of intermediate temperature embrittlement is inhibited by introducing the serrated grain boundaries. 
     
     
         8 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 7 , when tested at a temperature of 700° C., the strong-yet-ductile chemically complex alloy achieves a yield strength of at least 1,000 MPa along with a ductility of at least 20%. 
     
     
         9 . The strong-yet-ductile chemically complex alloy over a wide temperature range of  claim 4 , when tested at a temperature of 1,000° C., the strong-yet-ductile chemically complex alloy achieves an ultimate tensile strength of at least 300 MPa. 
     
     
         10 . A method for preparing a strong-yet-ductile chemically complex alloy over a wide temperature range, comprising:
 arc melting a mixture of raw materials having a purity >99.9 wt. % under a Ti-getter argon atmosphere to produce ingots;   turning over and remelting the ingots for at least eight times to reduce composition segregation, and dropping the ingot into a copper mold to obtained as-cast samples;   homogenizing the as-cast samples at 1000° C. to 1300° C. for 1 to 20 hours to obtained homogenized samples;   furnace-cooling the homogenized samples to 400° C. to 800° C. at a cooling rate of 1° C./min to 15° C./min, followed by air cooling to room temperature to obtained first cooled samples;   cold rolling the first cooled samples along a longitudinal direction with a reduction in thickness of 40% to 80%;   recrystallizing cold-rolled samples at 1000° C. to 1300° C. for 1 to 10 minutes to obtained recrystallized samples;   furnace-cooling the recrystallized samples to 400-800° C. at a cooling rate of 1-15° C./min followed by air cooling to room temperature to form second cooled samples with coarse primary L1 2  particles and serrated grain boundaries; and   aging the second cooled samples at about 600° C. to 900° C. for 4 to 100 hours and cooling aged samples to room temperature by air cooling to obtain the strong-yet-ductile chemically complex alloy with nanoscale secondary L1 2  particles.   
     
     
         11 . The method of  claim 9 , wherein the method further comprising aging the chemically complex alloy.