Influence of Heat Treatment Conditions on Microstructure of Ti-6Al-7Nb Alloy As Used Surgical Implant Materials

Abstract

The study involves mechanical deformation and heat treatment effect on the microstructure of the Ti-6Al-7Nb alloy which is used as surgical implanted materials. The observed properties of (alpha-beta) Ti-based alloy are strongly dependent on their microstructures. These alloys are heat treated by solution treatment and aging (STA) as an effective strengthening method for (alpha-beta) titanium alloys. Ti-6Al-7Nb alloy is hot rolled in the (alpha-beta) field and subjected to solution treatment above and below its beta transformation temperature. The solution treatments are applied at three different temperatures (850 o C, 930 o C and 950 o C) for one hour to these treatments. The solution treatment specimens are water quenched (WQ), normalizing [air cooled (AC) and annealed,[ furnace cooled(FC)] and subsequently aged the quenched and normalized specimens at 550 o C for 4 hours. Changes in the microstructure were observed from heat treatment action using optical microscopy, Atomic Absorption Spectroscopy (AAS) and phases analysis by X-ray diffraction (XRD). The microstructure examination results for as received alloy indicate alpha grains within a β-transformed matrix. The results also indicate that the grain size and percent of α /β for the heat treated specimens depend on heat treatment type and cooling media. The microstructure of specimens heat treated at 950 o C with air cooled shows fine duplex (α / β) structures which have excellent properties for surgical implanted field applications. Keyword: Titanium heat treatment, titanium alloy, implant material, heat treatment ,surgical materials. ‫ﺍﻟﺨﻼﺼﺔ‬ ‫ﺍﻟﻤﺠﻬﺭﻴﺔ‬ ‫ﺍﻟﺘﺭﺍﻜﻴﺏ‬ ‫ﻋﻠﻰ‬ ‫ﺍﻟﺤﺭﺍﺭﻴﻪ‬ ‫ﻭﺍﻟﻤﻌﺎﻤﻼﺕ‬ ‫ﺍﻟﻤﻴﻜﺎﻨﻴﻜﻲ‬ ‫ﺍﻟﺘﺸﻜﻴل‬ ‫ﺘﺄﺜﻴﺭ‬ ‫ﺍﻟﺩﺭﺍﺴﺔ‬ ‫ﺘﺘﻀﻤﻥ‬ ‫ﻟﺴﺒﻴﻜﺔ‬) (Ti-6Al-7Nb ‫ﺍﻟﺠﺭﺍﺤﻴﺔ‬ ‫ﺍﻟﺯﻭﺍﺭﻉ‬ ‫ﻓﻲ‬ ‫ﺍﻟﻤﺴﺘﺨﺩﻤﺔ‬. ‫ﺍﻟﺘﻴﺘﺎﻨﻴﻭﻡ‬ ‫ﺴﺒﻴﻜﺔ‬ ‫ﺨﻭﺍﺹ‬ ‫ﺒﺄﻥ‬ ‫ﻟﻭﺤﻅ‬ ‫ﺍﻟﻁﻭﺭ‬ ‫ﺜﻨﺎﺌﻴﺔ‬ (α /β) ‫ﻫﺫﻩ‬ ‫ﺍﻟﻤﺠﻬﺭﻴﺔ‬ ‫ﺍﻟﺘﺭﺍﻜﻴﺏ‬ ‫ﻋﻠﻰ‬ ‫ﺒﺸﺩﺓ‬ ‫ﺘﻌﺘﻤﺩ‬. ‫ﺒﻁﺭﻴﻘﺔ‬ ‫ﺍﻟﺴﺒﺎﺌﻙ‬ ‫ﻫﺫﻩ‬ ‫ﺘﻌﺎﻤل‬ ‫ﺍﻟﻤ‬ ‫ﻌﺎﻤﻠﺔ‬ ‫ﺍﻟﻤﺤﻠﻭﻟﻴﺔ‬ ‫ﺍﻟﺘﻴﺘﺎﻨﻴﻭﻡ‬ ‫ﺴﺒﺎﺌﻙ‬ ‫ﻟﺘﻘﻭﻴﺔ‬ ‫ﻓﻌﺎﻟﺔ‬ ‫ﻜﻁﺭﻴﻘﺔ‬ ‫ﻭﺍﻟﺘﻌﺘﻴﻕ‬ ‫ﺍﻟﻁﻭﺭ‬ ‫ﺜﻨﺎﺌﻴﺔ‬ (α /β). ‫ﻴﺘﻡ‬