颗粒尺寸对微波烧结多孔NiTi合金的显微结构及力学性能的影响

Effect of Particle Size on Microstructure and Mechanical Properties of Porous NiTi Alloys Prepared by Microwave Sintering

以不同颗粒尺寸的Ni/Ti粉末为原料,采用微波烧结技术制备了多孔NiTi合金,并系统考察了颗粒尺寸对多孔NiTi合金的显微结构和力学性能的影响。结果表明,随着颗粒尺寸的减小,多孔NiTi合金中的Ti2Ni和Ni3Ti第二相减少而单质Ni相消失。同时,多孔NiTi合金的孔隙形貌由带尖角的不规则形状向近球形转变。此外,多孔NiTi合金的孔隙率和孔径随着颗粒尺寸的增大而增大,而洛氏硬度、抗压强度和抗弯强度均下降。因此,减小颗粒尺寸有利于获得理想的显微结构(纯净的物相和均匀的孔隙结构)和提高微波烧结多孔NiTi合金的力学性能。

The porous NiTi alloys were prepared by microwave sintering from Ni/Ti powder with different particle sizes,and the effect of particle size on the microstructure and mechanical properties of the porous NiTi alloys was systematically investigated.The results show that the undesired Ti2Ni and Ni3Ti phases in the porous NiTi alloys decrease and the Ni phase disappears with decreasing the particle sizes.At the same time,the pore shapes of the porous NiTi alloys change from the irregular shape with sharp angles to the suborbicular shape.Moreover,both of the porosities and pore sizes of the porous NiTi alloys increase with increasing the particle sizes,while all of the Rockwell hardness,compressive strength and bending strength decrease.Therefore,the decrease of particle sizes is beneficial to obtain the microwave sintered porous NiTi alloys with desired microstructure(pure phase composition and uniform pore structure) and high mechanical properties.