Vitreous Metals and High-Strength Alloys

Small quantities of phosphides can act as crystallisation nuclei for components of alloys. High-strength materials for engine pistons are obtained by adding 0.01-0.03% P to certain Al/Si/Cu alloys. The AlP, which is formed, provides crystallisation nuclei for the growth of Si crystals of suitable size, which increase wear resistance. 

It may be possible to increase wear resistance by the introduction of boron phosphide, BP (Chapter 4.7), at aUoy and metal surfaces by laser or other treatments. 

Small amounts of ternary metal phosphides are important for special purposes. Thus, Florenskyite, FeTiP [22], is utilised for precipitation hardening in interstitial-free ferrite steels [23]. Other ternary phosphides with similar (FcjP type) crystal structures (Chapter 8.1), for example, NiCrP, MoNiP and FeNiP can strongly inflnence the microstructure and mechanical properties of glassy metal alloys. 

The so-called vitreons metals , amorphous alloys or metallic glasses with disordered structures can be obtained by extremely rapid chilling of molten mixtures of one or more metals with B, C, Si, or P In some cases, they may be obtained by ion sputtering, laser glazing or electrodeposition (Section 12.7). 

Many of these disordered alloys contain P and have compositions of the type (Fe, Co, Ni,)go (P, B, Si, C)2o. Typical are 

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