液-固体积比对消失模铸造Al/Cu双金属界面组织性能的影响

研究液-固体积比对消失模铸造Al/Cu双金属界面组织和性能的影响,并对Al/Cu双金属界面的形成机理进行讨论。结果表明:液-固体积比为3:1时Al/Cu双金属材料无法形成有效的冶金结合,当液-固体积比超过5:1时,Al/Cu双金属材料连接区域部分位置开始发生冶金结合;在发生冶金反应的情况下,Al/Cu双金属界面面均由Al₄Cu₉层,Al Cu层,Al₂Cu层和共晶反应层4层组成;随液-固体积比增大,由于凝固时间延长和铜基体的溶解增加的共同作用,共晶反应层组织出现先粗大后细化的变化。Al/Cu界面层的硬度在140～190HV之间,未呈明显的规律性,随着液-固体积比的增大,Al/Cu双金属材料的剪切强度先增加后减小,并在在7:1时达到最大值(81 MPa),且均从金属间化合物(IMCs)层发生断裂。

Effects of melt-to-solid volume ratio on microstructures and mechanical properties of Al/Cu bimetal interface in lost foam casting

The effects of the melt-to-solid volume ratio(VR)on microstructure and mechanical properties of the Al/Cu bimetal were studied,and the formation mechanism of the Al/Cu interface was discussed.The results show that the metallurgical bonding cannot be formed when the VR is 3:1.When the VR rises above5:1,the interface zone begins to form in part of the Cu substrate.The interfaces of the Al/Cu bimetals are composed of four different layers:Al4Cu9,AlCu,Al2Cu,and eutectic reaction layer.The hardness of the Al/Cu interface is between 140 and 190 HV.With the increase of the VR,the microstructure of the eutectic reaction layer first becomes coarse,followed by refinement,due to the combination of prolonged solidification time and the increased dissolution of Cu,and the shear strength of the Al/Cu bimetal increases first and then decreases.When the VR is 7:1,it reaches a maximum of 81 MPa,and both of them break from the intermetallic compounds(IMCs)layer.