Plastic single-axis zero-expansion composite material and preparation method thereof

Abstract

A plastic single-axis zero-expansion composite material and a preparation method thereof are provided, featuring incorporating an α-Fe second phase into a matrix of R2Fe17-type intermetallic compound, in which R refers to a rare earth element with a low atomic content of 4%. The material has simple synthesis steps and can be easily implemented, and the phase interface formed by the eutectic reaction is more stable than the composite structures obtained by the traditional solid-phase sintering, thereby realizing the regulation of the thermal expansion, and significantly improving the mechanical properties.

What is claimed is: 
     
         1 . A preparation method of a plastic single-axis zero-expansion composite material, wherein the preparation method incorporates an α-Fe phase as a second phase into an R 2 Fe 17 -type intermetallic compound, wherein the R 2 Fe 17 -type intermetallic compound exhibits negative thermal expansion, the α-Fe phase exhibits positive thermal expansion; and
 the plastic single-axis zero-expansion composite material having a wide temperature zone is obtained by regulating the positive thermal expansion and the negative thermal expansion by controlling a ratio of the α-Fe phase and the R 2 Fe 17 -type intermetallic compound, and an orientation of the R 2 Fe 17 -type intermetallic compound, wherein R is a rare earth element. 
 
     
     
         2 . The preparation method according to  claim 1 , wherein the preparation method comprises the following steps:
 step 1: providing two raw materials: a raw material of the R 2 Fe 17 -type intermetallic compound and a raw material of the α-Fe phase;   step 2: mixing the two raw materials of the step 1 into mixed raw materials;   step 3: smelting uniformly the mixed raw materials of step 2 to form a uniformly smelted sample by using an electric-arc furnace;   step 4: annealing the uniformly smelted sample of step 3 under a protective atmosphere; and   step 5: after the annealing of step 4 has ended, obtaining the plastic single-axis zero-expansion composite material.   
     
     
         3 . The preparation method according to  claim 2 , wherein in the step 1, purities of the raw material of the R 2 Fe 17 -type intermetallic compound and the raw material of the α-Fe phase are both >99.5%. 
     
     
         4 . The preparation method according to  claim 2 , wherein in the step 1, the R 2 Fe 17 -type intermetallic compound is of a hexagonal crystal system or a trigonal crystal system, wherein when R is a light rare earth element, the R 2 Fe 17 -type intermetallic compound is of a trigonal crystal system, and has a space group of R-3m, and when R is a heavy rare earth element, the R 2 Fe 17 -type intermetallic compound is of a hexagonal crystal system, and has a space group of P6 3 /mmC. 
     
     
         5 . The preparation method according to  claim 2 , wherein in the step 1 the α-Fe phase is of a cubic crystal system and has a space group of Im-3m. 
     
     
         6 . The preparation method according to  claim 2 , wherein the step 4 comprises placing the uniformly smelted sample under the protective atmosphere, and annealing at 1100° C. for at least 24 h, wherein the protective atmosphere is vacuum or an inert gas. 
     
     
         7 . The preparation method according to  claim 1 , wherein the R 2 Fe 17 -type intermetallic compound is a matrix phase, the α-Fe phase is a plastic second phase, and the plastic second phase is incorporated into the matrix phase to improve a mechanical behavior of the matrix phase, and by synergy between the matrix phase and the plastic second phase, inhibit an intrinsic brittleness of the R 2 Fe 17 -type intermetallic compound. 
     
     
         8 . A plastic single-axis zero-expansion composite material, prepared by using the preparation method according to  claim 1 , wherein a chemical formula of the single-axis zero-expansion composite material is R x Fe 1-x , wherein 0<x≤0.09, and R is a rare earth element. 
     
     
         9 . The plastic single-axis zero-expansion composite material according to  claim 8 , wherein the single-axis zero-expansion composite material comprises Ho 0.04 Fe 0.96 , and the Ho 0.04 Fe 0.96  exhibits a characteristic of zero expansion within a temperature interval of 100-335K, wherein a coefficient of linear expansion α 1  is 0.19×10 −6 . 
     
     
         10 . The plastic single-axis zero-expansion composite material according to  claim 8 , wherein the preparation method comprises the following steps:
 step 1: providing two raw materials: a raw material of the R 2 Fe 17 -type intermetallic compound and a raw material of the α-Fe phase;   step 2: mixing the two raw materials of the step 1 into mixed raw materials;   step 3: smelting uniformly the mixed raw materials of step 2 to form a uniformly smelted sample by using an electric-arc furnace;   step 4: annealing the uniformly smelted sample of step 3 under a protective atmosphere; and   step 5: after the annealing of step 4 has ended, obtaining the plastic single-axis zero-expansion composite material.   
     
     
         11 . The plastic single-axis zero-expansion composite material according to  claim 10 , wherein in the step 1, purities of the raw material of the R 2 Fe 17 -type intermetallic compound and the raw material of the α-Fe phase are both >99.5%. 
     
     
         12 . The plastic single-axis zero-expansion composite material according to  claim 10 , wherein in the step 1, the R 2 Fe 17 -type intermetallic compound is of a hexagonal crystal system or a trigonal crystal system, wherein when R is a light rare earth element, the R 2 Fe 17 -type intermetallic compound is of a trigonal crystal system, and has a space group of R-3m, and when R is a heavy rare earth element, the R 2 Fe 17 -type intermetallic compound is of a hexagonal crystal system, and has a space group of P6 3 /mmC. 
     
     
         13 . The plastic single-axis zero-expansion composite material according to  claim 10 , wherein in the step 1 the α-Fe phase is of a cubic crystal system and has a space group of Im-3m. 
     
     
         14 . The plastic single-axis zero-expansion composite material according to  claim 10 , wherein the step 4 comprises placing the uniformly smelted sample under the protective atmosphere, and annealing at 100° C. for at least 24 h, wherein the protective atmosphere is vacuum or an inert gas. 
     
     
         15 . The plastic single-axis zero-expansion composite material according to  claim 8 , wherein the R 2 Fe 17 -type intermetallic compound is a matrix phase, the α-Fe phase is a plastic second phase, and the plastic second phase is incorporated into the matrix phase to improve a mechanical behavior of the matrix phase, and by synergy between the matrix phase and the plastic second phase, inhibit an intrinsic brittleness of the R 2 Fe 17 -type intermetallic compound.