| Abstract: | omesolution treatmentsfor Ti 5 8 Al 4 8Sn 2 0Zr 1 0 Mo 0 34Si 0 90 Nd (1 # alloy) , Ti 6 3 Al 4 8 Sn 2 0 Zr 1 0 Mo 0 34 Si 0 90 Nd(2 # alloy) and Ti 6 8 Al 4 8Sn 2 0 Zr 0 5 Mo 0 34 Si 0 70 Nb 0 90 Nd (3 # alloy) several near alpha Titanium alloysat various temperaturesin (α+ β) two phaseregion havebeen carriedout. Theeffectsofsolution treat menttemperatureon theshape,size, distribution andvolumefraction ofthe primary alpha phase(αprim)havebeeninvestigated. Theresultsshowed thattheshape ofαprim did not depend onthesolution temperature, butthesize, the distribution and the volume fraction changed withthevariedsolutiontreatmenttemperature. Theprimaryalpha phaseprincipally precip itated atthe βgrain boundary regions atthe higher temperature nearthe Tα+ β/ β, and asthe temperature was dropped, αprim precipitated in a more uniform way. By energy spectrumanalysisof SEM, the elemental distributionsin primary αphase and transformed βphase(βtrans) havebeeninvestigated. The resultsshowed thatthe amount of Alelementin αprim is higherobviouslythanin βtransathighertemperature. Asthesolution temperature gotdropped theconcentrationsof aluminum elementgot moreuniform in both αprim and βtrans. Thehigher concentration of aluminum elementin αprim would play a importantrolein orderedα2 phase precipitation, and so have an importanteffecton the high temperature properties of the al loys. |
