(大連理工大學(xué) 材料工程系， 大連 116024)
摘 要: 采用脈沖激光焊研究了Ti-50.6%Ni(摩爾分?jǐn)?shù))合金細(xì)絲點(diǎn)焊， 對比分析了接頭與母材顯微組織、 相變行為、 Ni含量、 顯微硬度及應(yīng)力—應(yīng)變曲線的變化。 結(jié)果表明： 當(dāng)NiTi合金用做功能材料時(shí)， 激光焊接是可取的； 激光點(diǎn)焊接頭熔化區(qū)由樹枝晶組成， 熱影響區(qū)靠近熔池部分為粗大等軸晶， 靠近母材部分為細(xì)小等軸晶；激光焊會(huì)造成Ni的蒸發(fā)， 使接頭中Ni含量降低0.2%(摩爾分?jǐn)?shù))， 從而影響接頭的相變行為； 接頭抗拉強(qiáng)度可達(dá)母材的70%， 可恢復(fù)應(yīng)變達(dá)母材的92%。
關(guān)鍵字: NiTi合金； 激光焊； 超彈性； 組織
superelastic NiTi alloy wire
（ Department of Materials Engineering, Dalian University of Technology, Dalian 116024, China）
Abstract: Ti-50.6%Ni(mole fraction) wires were welded using pulsed YAG laser. The laser spot-welded joints were tested for the microstructure, transformation behavior, Ni-content, micro-hardness and stress—strain curves in comparison with the base metal. The results show that laser welding NiTi alloy is advisable when NiTi alloy is used as functional materials. The fusion zone features dendrite structure, the microstructures of heat-affected zone can be divided into two parts, i.e. coarse equiaxial crystals near the fusion zone and fine equiaxial crystals near the base metal. The transformation behavior of the joint is affected by the vaporization of Ni during the laser welding process. The ultimate tensile strength of the joint is up to 70% of the base metal, the maximum recoverable strain is up to 92% of the base metal.
Key words: NiTi alloy; laser welding; superelasticity; microstructure
