Investigation into the effect of substituting Mo by W on the behavior,during aging,of the maraging type ternary alloys

The substitution of W for Mo in the Fe-16.4 Ni-8.2 Mo alloys produces a dual component alloy: i) lath martensite containing 5 wt pet W and ii) 2 pct intermetallic phase, the composition of which is 33.3 Fe-4.4 Ni-62.3 W. The behavior of the two alloys Fe-16.4 Ni-8.2X (X)=Mo or W) is compared during heating (between 20 and 950°C) at a rate of 300°C/h. For both alloys, the martensite transforms into austenite in three successive steps by a predominantly diffusional mechanism. The behavior of the two alloys in similar during isothermal aging at temperatures less than or equal to 550°C. In fact, the aging process takes place in three successive stages which are studied using the small-angle X-ray scattering technique and electron microscopy.