電流強(qiáng)度對(duì)冷坩堝定向凝固N(yùn)i3Al金屬間化合物微觀組織的影響

電流強(qiáng)度對(duì)冷坩堝定向凝固N(yùn)i3Al金屬間化合物微觀組織的影響EFFECT OF CURRENT INTENSITY ON MICROSTRUCTURE OF Ni3Al INTERMETALLICS PREPARED BY DIRECTIONAL SOLIDIFICATION ELECTROMAGNETIC COLD CRUCIBLE TECHNIQUE

為改善Ni3Al合金的室溫塑性，研究了不同電流強(qiáng)度的直流電場(chǎng)對(duì)冷坩堝定向凝固N(yùn)i3Al合金微觀組織的影響。結(jié)果表明，在直流電場(chǎng)作用下，隨著電流強(qiáng)度的增加，Ni3Al合金的定向凝固組織的一次枝晶間距變小，凝固界面變得平直；當(dāng)未施加直流電流時(shí)，凝固組織由L12型結(jié)構(gòu)的Ni3Al基體和B2型結(jié)構(gòu)的NiAl析出相兩相組成。當(dāng)定向凝固過程中施加直流電流時(shí)，凝固組織中析出相由B2型NiAl相轉(zhuǎn)變?yōu)槌时訝?，晶面?duì)稱的孿晶馬氏體NiAl相。

In order to improve the room temperature ductility of Ni3Al alloy, Ni3Al intermetallics were prepared at different current intensities by directionally solidified （DS） in an electromagnetic cold crucible directional solidification furnace. The primary dendritic spacing (λ) decreases with the increasing of current intensity (A). And the Solid-liquid interface tend to straight and smooth as current intensity increasing. When the current intensity is 0A, the DS samples contain the L12 structure of Ni3Al and B2 structure of NiAl phase. When the DC current is applied the precipitated NiAl phase transformed into martensite NiAl phase from the NiAl-B2 type structure, martensite is thin, twin crystal symmetry.

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