Microstructure and mechanical properties of Al/Cu/Mg laminated composite sheets produced by the ARB proces

In the present study, an Al/Cu/Mg multi-layered composite was produced by accumulative roll bonding(ARB) through seven passes, and its microstructure and mechanical properties were evaluated. The microstructure investigations show that plastic instability occurred in both the copper and magnesium reinforcements in the primary sandwich. In addition, a composite with a perfectly uniform distribution of copper and magnesium reinforcing layers was produced during the last pass. By increasing the number of ARB cycles, the microhardness of the layers including aluminum, copper, and magnesium was significantly increased. The ultimate tensile strength of the sandwich was enhanced continually and reached a maximum value of 355.5 MPa. This strength value was about 3.2, 2, and 2.1 times higher than the initial strength values for the aluminum, copper, and magnesium sheets, respectively. Investigation of tensile fracture surfaces during the ARB process indicated that the fracture mechanism changed to shear ductile at the seventh pass.

菜籽油纳米润滑剂在平行通道转角挤压过程中的润滑性能（英文）

由于使用传统润滑剂存在生物风险,植物油已成为人们关注的焦点。此外,为了提高植物油在金属成型工艺等各种应用中的摩擦性能,纳米颗粒被用作添加剂。本文研究了平行通道转角挤压(PTCAP)过程中分散在菜籽油中的Al2O3和TiO2纳米颗粒的润滑性能。在三种润滑条件下进行了PTCAP实验,并在最大成形力、表面粗糙度和显微硬度方面对PTCAP加工通道进行了比较。实验结果表明,加入上述纳米颗粒可使最大变形力至少降低50%。此外,成型通道的表面粗糙度明显降低。

旋切钛基复合材料(Ti-MMC)的超细微粒粉尘排放（英文）

钛基复合材料(Ti-MMC)具有优异的特性和相容性,有望取代已广泛应用的商用钛和高温合金。尽管Ti-MMC具有优越的性能,但因生产成本高、工件基体的刚性和存在的磨料陶瓷颗粒等因素,被归类为加工性能差的极难切削材料。采用润滑方法加工Ti-MMCs的工艺参数很少被研究。考虑到可切削性能,选择了超细粒(UFPs)和细颗粒(FPs),研究了影响粉尘排放的因素。根据实验观察,无论使用哪种类型涂层,较高的流量水平会导致较少的超细粉,但没有观察到对细颗粒的显著影响。在类似的切削条件下,使用无涂层刀片时会排放较高水平的细颗粒。此外,切削速度对超细粉没有显著影响,但对细的颗粒有显著的影响,且与插入类型无关。