The variations, with temperature, of the morphology of metastable phases in 3000 & 5000 Aluminium alloys

<p class="MsoNormal" style="margin-bottom: 0.0001pt; direction: ltr; unicode-bidi: embed; text-align: left;"><span style="font-size: 9.0pt; font-family: 'Cambria','serif'; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi;">&nbsp;Recent studies have shown that in 3000 and 5000 series aluminum alloys metastable phases are present that their size and morphology change with a &nbsp;semi dispersion treatment. Nevertheless, there is no consensus about the temperature to achieve the highest fragmentation of metastable phase. On the whole, the size and distribution of dispersoids are dependent on the fabricating method and complementary steps. In this research, the effect of the temperature of "post treatment" on characteristic of metastable phase and improving the impact strength of the alloys as extruded was investigated .</span><span style="font-size: 9.0pt; font-family: 'Cambria','serif'; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi;">By hot extrusion of 4-inch billet, produced by melting and casting of used beverage aluminum cans, a profile with a rectangular cross-section of 10 &times; 20 mm was obtained. The samples wire cut from the profile. Then, "semi dispersion treatment" was done in a way, in that the samples which were quasi dissolved at 600&deg;C for 8h followed by water quenching, and then semi aged at temperatures of 300, 400, and 500&deg;C for 1 hour. The Charpy impact test was carried out </span><span style="font-size: 9.0pt; font-family: 'Cambria','serif';">at room temperature according to ASTM standard </span><span style="font-size: 9.0pt; font-family: 'Cambria','serif'; mso-fareast-font-family: Calibri; mso-fareast-theme-font: minor-latin; mso-bidi-font-family: Arial; mso-bidi-theme-font: minor-bidi;">E23-06.&nbsp;</span><span style="font-family: Cambria, 'serif'; font-size: 9pt;">The results of the Charpy impact test showed that with rising semi aging temperature from 300 to 500 &deg;C, impact toughness increases from 72 to 87 (J/cm&sup2;). Meanwhile, the impact strength of the reference sample (after extrusion and without semi dispersion treatment) is 55 (J/cm&sup2;).&nbsp;</span><span style="font-family: Cambria, 'serif'; font-size: 9pt;">&nbsp;</span><span style="font-family: Cambria, 'serif'; font-size: 9pt;">The change in impact strength is in the result of morphology change and&nbsp;</span><span style="font-family: Cambria, 'serif'; font-size: 9pt;">distribution.</span> <!-- [if gte msEquation 12]><m:oMath><m:sSub><m:sSubPr><span style='font-size:10.0pt;mso-ansi-font-size:10.0pt;mso-bidi-font-size:10.0pt; font-family:"Cambria Math","serif";mso-ascii-font-family:"Cambria Math"; mso-hansi-font-family:"Cambria Math";mso-bidi-font-family:"B Mitra"; mso-bidi-language:FA'><m:ctrlPr></m:ctrlPr></span></m:sSubPr><m:e><i style='mso-bidi-font-style:normal'><span style='font-size:10.0pt;font-family: "Cambria Math","serif";mso-fareast-font-family:Calibri;mso-bidi-font-family: "B Mitra";mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language: FA'><m:r>Mg</m:r></span></i></m:e><m:sub><span style='font-size:10.0pt; font-family:"Cambria Math","serif";mso-fareast-font-family:Calibri; mso-bidi-font-family:"B Mitra";mso-ansi-language:EN-US;mso-fareast-language: EN-US;mso-bidi-language:FA'><m:r><m:rPr><m:scr m:val="roman"/><m:sty m:val="p"/></m:rPr>2</m:r></span></m:sub></m:sSub><i style='mso-bidi-font-style:normal'><span style='font-size:10.0pt;font-family: "Cambria Math","serif";mso-fareast-font-family:Calibri;mso-bidi-font-family: "B Mitra";mso-ansi-language:EN-US;mso-fareast-language:EN-US;mso-bidi-language: FA'><m:r>Si</m:r></span></i></m:oMath><![endif]--><!-- [if !msEquation]--> &nbsp; <!--[endif]-->