摘要
采用多物理场活化烧结微成形技术（Micro-FAST）,低温（850℃）、短时间内（约8 min）成功制备了Φ4 mm×4 mm的Ni Ti微型圆柱,并研究了升温速率对制备Ni Ti合金致密度的影响。结果表明,试样在快速升温阶段发生最大的收缩量,直接影响了试样的烧结质量。在升温速率为25~125℃/s的范围内,随着升温速率的提高,Ni Ti合金的相对密度降低。升温速率越大（电流越大）,大电流促进原子扩散,形成富Ni区,利于Ni Ti_2和Ni_3Ti相的形成,并加剧Kirkendall效应,生成更多孔隙;试样在电流作用下产生局部高温,促使局部液相生成,融化周围粉末生成孔隙。
A novel method Micro-forming Fields Activated Sintering Technology（Micro-FAST） was applied to prepare Ni Ti alloy.Cylindrical specimens with a diameter of 4 mm and a height of 4 mm were prepared at 850 ℃in a short time（about 8 min）.The effect of heating rate on the density of Ni Ti alloy was investigated.The results show that the axial reduction in rapid heating stage is the biggest among the four sintering stages of Micro-FAST,which directly influences the quality of sintered samples.In the experimental range from 25 ℃/s to 125 ℃/s,the relative density of the Ni Ti alloy sintered by Micro-FAST is decreased with the increasing heating rates.The higher the heating rate,the bigger the electric current,which accelerates atomic diffusion.As a result,Ni enrichment appears,so Ni Ti_2 and Ni_3 Ti are easier to be formed,and the effect of Kirkendall is heightened.Meanwhile,local liquid-phase is produced by local high temperature under electric current,which promotes the fusions of particles and the formation of pores.
出处
《稀有金属材料与工程》
SCIE
EI
CAS
CSCD
北大核心
2016年第7期1816-1820,共5页
Rare Metal Materials and Engineering
基金
国家自然科学基金(51275322)
