Brazeability evaluation of Ti-Zr-Cu-Ni-Co-Mo filler for vacuum brazing TiAl-based alloy

Ti-47Al-2Nb-2Cr-0.15B(mole fraction,%)alloy was vacuum brazed with amorphous and crystalline Ti.25Zr-12.5Cu-12.5Ni-3.0Co-2.0Mo(mass fraction,%)filler alloys,and the melting,spreading and gap filling behaviors of the amorphous and crystalline filler alloys as well as the joints brazed with them were investigated in details.Results showed that the amorphous filler alloy possessed narrower melting temperature interval,lower liquidus temperature and melting active energy compared with the crystalline filler alloy,and it also exhibited better brazeability on the surface of the Ti.47Al.2Nb.2Cr.0.15B alloy.The TiAl joints brazed with crystalline and amorphous filler alloys were composed of two interfacial reaction layers and a central brazed layer.Under the same conditions,the tensile strength of the joint brazed with the amorphous filler alloy was always higher than that with the crystalline filler alloy.The maxmium tensile strength of the joint brazed at 1273 K with the amorphous filler alloy reached 254 MPa.

基于LS-SVM的铜铬合金挤压加工挤压力预测

提出一种最小二乘支持向量机的Cu-0.75Cr铜合金反挤压力预测新模型。以断面缩减率、凸模锥角和挤压温度这3个主要工艺参数作为影响因素,以反挤压过程的挤压力为影响对象,通过最小二乘支持向量机模型建立影响因素和影响对象之间的复杂非线性关系。以正交实验数据为样本对模型进行训练,用训练好的模型预测在一定反挤压条件下Cu-0.75Cr铜合金的挤压力。结果表明:该模型不仅预测精度和处理速度大大高于人工神经网络预测模型,而且建模速度也比标准支持向量机快,实际预测误差小于3%。