热等静压烧结Nd-Fe-B永磁体

Microstructural study on Nd-Fe-B permanent magnets prepared by hot isostatic pressing sintering

热等静压烧结通常用来促进合金致密化和细化组织。本文尝试对Nd32.54Dy0.5Fe65.36Al0.6B1.0预烧结体分别进行热等静压烧结和常规烧结,旨在研究热等静压烧结能否促进Nd Fe B合金的致密化和晶粒细化。首次发现:高温热等静压烧结时,预烧结样品内的部分富Nd液相外流,在样品内形成空洞,被高压Ar气填充,造成样品不能收缩,磁体的密度比常规烧结磁体的低,力学性能明显恶化;且液相外流引起晶粒转动,导致取向度降低,最终磁体的剩磁和磁能积降低。

Two sintering techniques, hot isostatic pressing (HIP) and pressureless sintering (PS), were used to verify the effect of HIP on density and microstructure and magnetic properties of Nd32.54Dy0.5Fe65.36B1.0 magnets. It was firstly concluded that the density of the magnets by HIP was less than that by PS since empty holes were always left and filled with Ar gas in the magnets after Nd-rich liquid phase was pressed out by high pressure during HIP sintering. In addition, alignment degree of Nd2Fe14B grains in the magnets by HIP sintering was weakened. Consequently, the lower magnetic properties of the magnets by HIP sintering than by PS were caused.