The effect of alloyed iron powder on the properties of metal/diamond composites

Iron is added in the form of iron-phosphorus and iron-copper pre-alloyed powder to increase the strength of the metal matrix and the diamond/metal composite material, and improve the holding power and wear resistance of diamond. 1. The experimental method uses reduced iron powder smaller than 75μm and iron-copper pre-alloy powder (Fe-7.2Cu-0.8Sn-0.05 other) and iron-phosphorus pre-alloy powder (Fe-0.51P-0.15C) produced by Anshan Iron and Steel Powder Factory As the basic powder, prepare the matrix composition according to the following formula: (volume fraction)% group FeFe-PFe-CuCuNiCoSnWCA4

231.5 3016.

3 34.727.

Note: A4 is self-made master pre-alloy powder. Samples are prepared by hot pressing. The equipment is a direct-heating hot press and graphite molds. The hot pressing is carried out in air. The temperature is 850-870℃, the holding time is 4-6min, and the hot pressing pressure is 35Mpa. HR-150A hardness tester is used to determine the hardness of the substrate; the three-point bending strength is measured on the WE-10A hydraulic universal material testing machine, the sample size is 5×5×40mm; the Archimedes method is used to measure the density of the sample; Self-made abrasion testing machine to test the abrasion resistance of the substrate.

The results are as follows:

Relative density of base material:% Flexural strength: MPa Hardness: HRC Wear rate: Composite material strength: MPa




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2. Conclusion and analysis 2.1 The pre-alloyed powder can improve the density, strength and wear resistance of the metal matrix.

a. The Cu and Sn components in the Fe-Cu pre-alloyed powder, when the hot pressing temperature is higher than its melting point, a liquid phase will be formed inside the alloyed iron powder, which is conducive to the densification of the hot-pressed material and makes it The density reaches 99.6%. In addition, because the role of copper is to strengthen ferrite, the use of alloyed powder is conducive to the homogenization of alloying elements, fully exerting the solid solution strengthening effect of copper, and improving the bending strength of the matrix.

b. When Fe-P pre-alloyed powder is used as the base powder, on the one hand, due to the large difference between the atomic radii of phosphorus and iron, an interstitial solid solution is formed for solid solution strengthening. On the other hand, the addition of phosphorus stabilizes the α-Fe phase, and the high diffusion coefficient of iron in the α-Fe phase increases the densification degree of sintering, and its density reaches 99.6%. An increase in density leads to an increase in strength.

c. Because the addition of Fe-based pre-alloyed powder increases the relative density of the matrix, making it closer to the theoretical density value, and the wear resistance of the matrix is ​​related to the porosity. The density is low, the porosity is large, and the connection between particles is weakened. The surface is rough, the abrasion resistance is low. Therefore, while increasing the relative density of the matrix, the wear resistance is improved.

2.2 The influence of the particle size of the base powder on the hardness of the matrix: reducing the particle size is beneficial to increase the hardness of the material