ASTM_F_2004_-_05_2010.pdf

Designation:F200405(Reapproved 2010)Standard Test Method forTransformation Temperature of Nickel-Titanium Alloys byThermal Analysis1This standard is issued under the fixed designation F2004;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method defines procedures for determining thetransformation temperatures of nickel-titanium shape memoryalloys.1.2 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.3 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and to determine theapplicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2E473 Terminology Relating to Thermal Analysis and Rhe-ologyE967 Test Method for Temperature Calibration of Differen-tial Scanning Calorimeters and Differential Thermal Ana-lyzersE1142 Terminology Relating to Thermophysical PropertiesF2005 Terminology for Nickel-Titanium Shape MemoryAlloys3.Terminology3.1 Specific technical terms used in this test method arefound in Terminologies E473,E1142,and F2005.4.Summary of Test Method4.1 This test method involves heating and cooling a testspecimen at a controlled rate in a controlled environmentthrough the temperature interval of the phase transformation.The difference in heat flow between the test material and areference material due to energy changes is continuouslymonitored and recorded.Absorption of energy due to a phasetransformation in the specimen results in an endothermic peakon heating.Release of energy due to a phase transformation inthe specimen results in an exothermic peak on cooling.5.Significance and Use5.1 Differential scanning calorimetry provides a rapidmethod for determining the transformation temperature(s)ofnickel-titanium shape memory alloys.5.2 This test method uses small,stress-free,annealedsamples to determine whether a sample of nickel-titanium alloycontaining nominally 54.5 to 56.5%nickel by weight isaustenitic or martensitic at a particular temperature.Sincechemical analysis of these alloys does not have sufficientprecision to determine the transformation temperature bymeasuring the nickel to titanium ratio of the alloy,directmeasurement of the transformation temperature of an annealedsample of known thermal history is recommended.5.3 This test method is useful for quality control,specifica-tion acceptance,and research.5.4 Transformation temperatures derived from differentialscanning calorimetry(DSC)may not agree with those obtainedby other test methods due to the effects of strain and load on thetransformation.6.Interferences6.1 Make sure the material to be tested is homogeneoussince milligram sample quantities are used.6.2 Take care in preparing the sample.Cutting and grindingcan cause cold work,which affects the transformation tempera-ture.Oxidation during heat treatment can change the thermalconductance of the sample.6.3 Set the gas flow to provide adequate thermal conductiv-ity in the test cell.7.Apparatus7.1 Use a differential scanning calorimeter capable of heat-ing and cooling at rates up to 10C/min and of automatically1This test method is under the jurisdiction ofASTM Committee F04 on Medicaland Surgical Materials and Devices and is the direct responsibility of SubcommitteeF04.15 on Material Test Methods.Current edition approved June 1,2010.Published September 2010.Originallyapproved in 2000.Last previous edition approved in 2005 as F2004 05.DOI:10.1520/F2004-05R10.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 recording the differential energy input between the specimenand the reference to the required sensitivity and precision.7.2 Use sample capsules or pans composed of aluminum orother inert material of high thermal conductivity.7.3 Use helium gas purge supply.See 10.3.1.7.4 Use an analytical balance with a capacity of 100 mgcapable of weighing to the nearest 0.1 mg.8.Sampling8.1 Use a sample size of 25 to 45 mg.Cut the sample tomaximize surface contact with the(DSC)sample pan.8.2 Anneal the sample at 800 to 850C for 15 to 60 min invacuum or inert atmosphere,or in air with adequate protectionfrom oxidation.Rapidly cool the sample to prevent precipita-tion of phases which may change transformation temperatureof the alloy.8.3 Clean the sample of all foreign materials such as cuttingfluid.If the sa