定向凝固参数对二元铝锂合金共晶生长及组织结构的影响

本文研究了定向凝固参数对二元铝锂合金共晶生长及组织结构的影响。实验发现，Ｌｉ少于７ｗｔ％的合金中，晶体不能以共晶方式生长。Ｌｉ多于７ｗｔ％的合金中，可以获得平面生长的共晶组织，凝固参数对晶体生长方式及组织形貌有显著的影响     

浅议多芯片焊接工装设计

文章以微波功率多芯片真空焊接试验用工装(2Z-6P)设计为例,阐述了工装功能构件设计思路及其关键细节。提出了依据TRIZ冲突解决原理,在明确设计的输入、输出要求的前提下,分析了工装设计的构成要素,从中梳理核心冲突要素,再寻求具有针对性的冲突要素有效解的实效方法。展示工装工程验证结果,旨在于促进精密工装设计水平提升和工程中的实际应用。     

Microstructure evolution of a hypereutectic Nb–Ti–Si–Cr–Al–Hf alloy processed by directional solidification

In this work, the Nb–14Si–24Ti–10Cr–2Al–2Hf–0.1Y alloy(at.%) was processed by the liquid–metal-cooled directional solidification(DS) at 1750 C with withdrawal rates of 1.2, 6,18 mm/min and post heat treatment(HT) at 1450 C for 10 h. The microstructures of the directionally solidified and heat treated samples were investigated. The results show that the microstructure of directionally solidified alloy mainly consists of petaloid Nbss+ Nb5Si3eutectics and Ti-rich Nbss+ Nb5Si3+ Cr2Nb eutectics. With the increase of withdrawal rate, the primary Nb5Si3is eliminated, Nbss+ Nb5Si3eutectic cells turn round and connected with the microstructure refinement and Nbss+ Nb5Si3+ Cr2Nb eutectics turn to a river-like morphology. After heat treatment,Nbss+ Nb5Si3+ Cr2Nb eutectics disappeared and petaloid Nbss+ Nb5Si3eutectics turn to a specific fiber-mesh structure gradually, which is promoted by higher withdrawal rates. Furthermore,both the volume fraction of Cr2Nb and the content of Cr in Nbssof Nbss+ Nb5Si3eutectics change regularly with the increase of withdrawal rate and heat treatment at 1450 C for 10 h.