Phase Transformations in Binary Alloys under High Pressure

Abstract

Cherno gol ov ka, Mo scow di stri ct, 142432, R ussia H igh-pressure stu dies of bi nar y alloy systems displ ay some speci Ùc features connected w ith comp osition referring as a variable parameter . In a tw o-comp onent system under pressure there are observed transf ormations , w hich do not occur in a one-comp onent system. In particular, there is a formation of a single phase from a mi xture of tw o phases or a decomp ositio n of a unif orm phase into two phases of di˜erent comp ositi ons. A lloys of I n and Sn w ith neighb ouring elements give us examples of these kinds of transformations. Studies on binary alloys w ith applicati on of pressure pro vide exp erimental evidences that the alloy comp ositi on or electron concentration is one of the main factor for structural phase stability follow ing from H ume { Rothery rule. PACS numb ers: 61.50.K s, 62.50. + p, 61. 66.Dk I n t r o d u ct io nHi gh-pressure studi es a re mai nly focused on elements or on com p ounds alrea dy exi sti ng at a mbi ent pressure, e.g. on one-comp onent or qua si-one-comp onent system s. Investi g ati ons on bi na ry and mul ti -comp onent system s under pressure are l arg ely con Ùned to gi ven al l oy com p ositi on. For a two -comp onent system along wi th two therm odyna m i c pa ra meters, pressure and tem p erature, one ha s to consider an addi ti o nal vari abl e pa ra meter | com positi on. Thi s o˜ers f or a bi nary system an addi ti ona l degree of f reedom i n pha se equi l i bri a and al l ows the o ccurrence of pha se tra nsf orm ati ons under pressure, whi ch do no t occur i n a one-com p onent system .A bi na ry com p ound of a stoi chi om etri c comp ositi on i n hi g h-pressure studi es i s usual l y appro ached to a quasi-one-com p onent system, however thi s consi derati on coul d b e appl i ed wi th certa i n restri cti ons. It i s often observed tha t when accordi ng to therm odyna mi c equi l i bri um condi ti ons a bi nary com p ound shoul d decom p ose,

The stability of the rhombohedral -Hg phase alloyed with Sn under high pressure up to 30 GPa

“…Binary alloy systems display under pressure the evolution of phase equilibria including the following effects [1][2][3]:…”