Sintering Prealloyed Powders Fe-Ni-Cu-Mo Modified by Boron Base on Thermodynamic Investigations

Abstract

One of the methods to reduce porosity and increase mechanical properties of Fe-Ni-CuMo powder type is applying activated sintering with the boron powder. In the experiments, a diffusion bonded prealloyed powder type Distaloy SA (Fe-1.75%, Ni-1.5%, Cu-0.5%, Mo) was used alloyed by 0.2, 0.4, and 0.6 mas.% elemental boron powder with the addition of 0.8 mas.% of zinc stearate lubricant. Powders were 15 min blended, compacted and then sintered. The sintering process was elaborated in detail based on microstructure investigations and thermodynamic analysis, which showed that the liquid phase has to be formed as a result of eutectic reaction between matrix elements (Fe, Mo, Ni) and mixed boride (Fe, Mo, Ni) 2 B. In alloys with boron excess, the liquid phase may occur already a 1176°C in conformity with the reaction: L ↔ γ-Fe + Fe 2 B. Its quantity is increased with liquid solution formed in the eutectic reaction running between boron and copper at 1027°C. If the system tends to be in equilibrium, the chemical composition of the liquid solution should be shifted toward higher Fe levels.

Microstructure and Mechanical Properties of Modified 316L Stainless Steel Alloy for Biomedical Applications Using Powder Metallurgy

“…Relative densification of 94.40% was noted for S2 samples containing 0.5 wt.% titanium, whereas close densification of 89.14% was seen for 2 wt.% titanium-added samples. The inclusion of boron improved the densification process significantly, as reported in the literature [44][45][46]. Its addition kept the sintered density of samples close to that of pure 316L stainless steel samples.…”