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The elements W and Nb with paremagnetism and grain refinement was selected according to the magnetostrictive theory and the fine grain strengthening method. The thermodynamic software Factsage was used in alloy aided design. The samples with a low coefficient of thermal expansion (CTE) and a high strength were made by W+Nb binary alloying of FeNi36, forging and heat treatment. The mechanism of the low coefficient of thermal expansion and the high strength was analyzed by means of the results of Chemical analysis, metallographic and scanning electron microscopy, grain size, microhardness and CTE testing. The result shows that the elements of W+Nb have good grain refinement effect, the binary alloying can make the microhardness of matrix improved and maintain it at the lower CTE.