六四金属物理的金德在、王凤芝小组的论文题目是“氯化钠单晶体中位错观察”。在半年的论文工作中,他们对二千五百多个样品进行了三千多次观察,拍摄了三百多张照片。除了验证前人的结论外,也提出了某些新的看法,把“浸蚀——退火——再浸蚀”的方法试用到亚晶界和位错运动过程的观察方面。实践证明。这是一个行之有效的 Jindu Kim of the June 4th Metallurgical Physics Group, Wang Fengzhi’s paper entitled “Dislocation Observation in Single Crystal Sodium Chloride”. In their six-month dissertation work, they conducted more than 3,000 observations on over 2,500 samples and photographed more than 300 photos. In addition to verifying the conclusions of the predecessors, some new ideas have also been put forward to try the “etch-anneal-re-etch” method to observe subgrain boundaries and dislocation motion. Practice proved. This is a valid one