인장강도에서 연신률이 낮습니다. 높일 수 있는 화학성분?

<img src="https://t1.daumcdn.net/cfile/cafe/2373664C515468380F" class="txc-image" style="FLOAT: none; CLEAR: none" actualwidth="539" border="0" hspace="1" vspace="1" width="539" id="A_2373664C515468380F67AC"/>     <img src="https://t1.daumcdn.net/cfile/cafe/16285848515468590F" class="txc-image" width="601" style="WIDTH: 601px; FLOAT: none; CLEAR: none" actualwidth="703" border="0" hspace="1" vspace="1" height="481" id="A_16285848515468590F6B8C"/>      ☆황동의 기계적 성질은 아연함유량에 따라 달라지는데,            인장강도는 아연40%정도에서 최대가되고,            연신률은 아연30%정도에서 최대가된다.   <img src="https://t1.daumcdn.net/cfile/cafe/117F3B3451546E9016" class="txc-image" width="991" style="WIDTH: 991px; FLOAT: none; CLEAR: none" actualwidth="1024" border="0" hspace="1" vspace="1" height="346" id="A_117F3B3451546E9016E32D"/>   <?xml:namespace prefix = v /><v:shapetype id=_x0000_t75 path="m@4@5l@4@11@9@11@9@5xe" stroked="f" filled="f" o:preferrelative="t" o:spt="75" coordsize="21600,21600"><v:stroke joinstyle="miter"></v:stroke><v:formulas><v:f eqn="if lineDrawn pixelLineWidth 0"></v:f><v:f eqn="sum @0 1 0"></v:f><v:f eqn="sum 0 0 @1"></v:f><v:f eqn="prod @2 1 2"></v:f><v:f eqn="prod @3 21600 pixelWidth"></v:f><v:f eqn="prod @3 21600 pixelHeight"></v:f><v:f eqn="sum @0 0 1"></v:f><v:f eqn="prod @6 1 2"></v:f><v:f eqn="prod @7 21600 pixelWidth"></v:f><v:f eqn="sum @8 21600 0"></v:f><v:f eqn="prod @7 21600 pixelHeight"></v:f><v:f eqn="sum @10 21600 0"></v:f></v:formulas><v:path o:connecttype="rect" gradientshapeok="t" o:extrusionok="f"></v:path><?xml:namespace prefix = o /><o:lock aspectratio="t" v:ext="edit"></o:lock></v:shapetype><v:shape style="POSITION: absolute; MARGIN-TOP: 16pt; WIDTH: 221.11pt; HEIGHT: 161.6pt; v-text-anchor: top; mso-position-vertical-relative: line; mso-position-vertical: absolute; mso-position-horizontal-relative: text; mso-position-horizontal: absolute" id=_x179048272 type="#_x0000_t75"><v:imagedata src="file:///C:\Users\ADMINI~1\AppData\Local\Temp\Hnc\BinData\EMB000010707f4f.bmp" o:title="EMB000010707f4f"></v:imagedata><?xml:namespace prefix = w /><w:wrap type="topAndBottom"></w:wrap></v:shape>       ☆    청동의 기계적 성질 인장강도는주석함유량에이증가하면증가하는데,                  연신률은 주석 함유량 7~10%일 때  최대로 되고                                             그 이상이 되면 급격히 떨어진다.     <img src="https://t1.daumcdn.net/cfile/cafe/1225B33C51546FD10F" class="txc-image" width="957" height="480" style="WIDTH: 957px; FLOAT: none; HEIGHT: 480px; CLEAR: none" actualwidth="1024" border="0" hspace="1" vspace="1" id="A_1225B33C51546FD10F0F19"/>